1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Vaselesa [24]
3 years ago
14

joanna went school supply shopping she spent $35.98 on notebooks and pencils notebooks cost $2.30 each and pencils cost $1.42 ea

ch she bought a total of 21 notebooks and pencils how many of each did she buy
Mathematics
1 answer:
Mumz [18]3 years ago
6 0

Joanna bought 7 notebooks and 14 pencils

Step-by-step explanation:

Step 1 :

Let x denote the number of notebooks and y denote the number of pencils Joanna bought.

Cost of one notebook = $ 2.30

Cost of one pencil = $1.42

Step 2 :

Total of notebooks and pencils bought  = 21

=> x + y = 21 => y = 21-x

Total cost of notebooks and pencils = $35.98

=> 2.3x + 1.42y = 35.98

Substituting y = 21- x here , we have,

2.3x + 1.42 ( 21-x) = 35.98

2.3x + 29.82 - 1.42x = 35.98

0.88 x = 6.16

=> x = 7

y = 21-x = 21-7 = 14

Step 3 :

Answer :

Joanna bought 7 notebooks and 14 pencils

You might be interested in
Assume you have noted the following prices for books and the number of pages that each book contains. Book Pages (x) Price (y) A
belka [17]

Answer:

a) y=0.00991 x +1.042  

b) r^2 = 0.7503^2 = 0.563

c) r=\frac{7(30095)-(4210)(49)}{\sqrt{[7(2595100) -(4210)^2][7(354) -(49)^2]}}=0.7503  

Step-by-step explanation:

Data given

x: 500, 700, 750, 590 , 540, 650, 480

y: 7.00, 7.50 , 9.00, 6.5, 7.50 , 7.0, 4.50

Part a

We want to create a linear model like this :

y = mx +b

Wehre

m=\frac{S_{xy}}{S_{xx}}  

And:  

S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}  

S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}  

With these we can find the sums:  

S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}=2595100-\frac{4210^2}{7}=63085.714  

S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i){n}}=30095-\frac{4210*49}{7}=625  

And the slope would be:  

m=\frac{625}{63085.714}=0.00991  

Nowe we can find the means for x and y like this:  

\bar x= \frac{\sum x_i}{n}=\frac{4210}{7}=601.429  

\bar y= \frac{\sum y_i}{n}=\frac{49}{7}=7  

And we can find the intercept using this:  

b=\bar y -m \bar x=7-(0.00991*601.429)=1.042  

And the line would be:

y=0.00991 x +1.042  

Part b

The correlation coefficient is given by:

r=\frac{n(\sum xy)-(\sum x)(\sum y)}{\sqrt{[n\sum x^2 -(\sum x)^2][n\sum y^2 -(\sum y)^2]}}  

For our case we have this:

n=7 \sum x = 4210, \sum y = 49, \sum xy = 30095, \sum x^2 =2595100, \sum y^2 =354  

r=\frac{7(30095)-(4210)(49)}{\sqrt{[7(2595100) -(4210)^2][7(354) -(49)^2]}}=0.7503  

The determination coefficient is given by:

r^2 = 0.7503^2 = 0.563

Part c

r=\frac{7(30095)-(4210)(49)}{\sqrt{[7(2595100) -(4210)^2][7(354) -(49)^2]}}=0.7503  

4 0
3 years ago
Can someone help me with these both
Anna [14]
Hello,
so all you have to do is match the abbreviations to the triangles. The abbreviations stand for what is the SAME in both triangles, denoted by similar markings on equal sides and angles.

Abbreviations:
SSS = Side-Side-Side
SAS = Side-Angle-Side
ASA = Angle-Side-Angle
AAS = Angle-Angle-Side
HL = Hypotenuse-Leg

* Note - the angle side angle must go around the triangle in that order. ASA has the side BETWEEN the congruent angles.. SSA does NOT work.

(9.) ASA
(10.) AAS
(11.) SSS
(12.) No way to tell if congruent. (only 3 angles no side)
(13.) ASA
(14.) SAS
(15.) HL

7 0
3 years ago
#1 Factors Which of these numbers is a factor of 49? a. 9 b. 7 C. 6 d. 5​
Vesna [10]

Answer = b. 7

THANK YOU FOR LISTENING TO MY TED TALK

8 0
2 years ago
Evaluate the difference quotient for the given function. Simplify your answer.
nasty-shy [4]

I suppose you mean

f(x) = \dfrac{x+5}{x+1}

Then

f(3) = \dfrac{3+5}{3+1} = \dfrac84 = 2

and the difference quotient is

\dfrac{f(x)-f(3)}{x-3} = \dfrac{\frac{x+5}{x+1}-2}{x-3} \\\\ \dfrac{f(x)-f(3)}{x-3} = \dfrac{\frac{x+5-2(x+1)}{x+1}}{x-3} \\\\ \dfrac{f(x)-f(3)}{x-3} = \dfrac{-x+3}{(x+1)(x-3)} \\\\ \dfrac{f(x)-f(3)}{x-3} = \boxed{-\dfrac{x-3}{(x+1)(x-3)}}

If it's the case that <em>x</em> ≠ 3, then (<em>x</em> - 3)/(<em>x</em> - 3) reduces to 1, and you would be left with

\dfrac{f(x)-f(3)}{x-3}\bigg|_{x\neq3} = -\dfrac1{x+1}

4 0
2 years ago
Giving brainliestttt
Nataly [62]

Answer:

Jupiter is so big that all the other planets in the solar system could fit inside it. More than 1,300 Earths would fit inside Jupiter. Jupiter is the fifth planet from the sun. From Earth, it is almost always the second brightest planet in the night sky.

7 0
2 years ago
Other questions:
  • What is the equation of the line that is parallel to y-3x=2 and that passes through (6,1)?
    9·2 answers
  • What is the ordered pair point of H?
    12·1 answer
  • What are 5 ways that graph can be misleading ?
    9·2 answers
  • Diamond bought a few swirl marbles and divided it equally among four of her friends and her brother, Jordan. While playing, Jord
    7·2 answers
  • 5.4.4 Practice Modeling: Two variable systems of inequalities
    5·1 answer
  • What is the denominator for 2/3 ?
    10·2 answers
  • Find the domain of this equation {-2
    10·1 answer
  • A rocket is launched from a tower. The height of the rocket, y in feet, is related to the time after launch, x in seconds, by th
    15·1 answer
  • Please help me with this ​
    15·1 answer
  • Selena earned $200 last month babysitting. She used 25 of her earnings to buy a video game. How much did she spend on the video
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!