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Tpy6a [65]
4 years ago
12

4x+15y=13 3x+5y=16 solving systems by elimination

Mathematics
1 answer:
docker41 [41]4 years ago
6 0
4x+15y=13 (1)
3x+5y=16  (2)
(2) * 3 --> 9x+15y=48 becomes (3)
(3) - (1) 
5x=35
x=7
sub x =7 into (1)
4(7)+15y=13
28+15y=13 
-28         -28
15y= -15
y= -15/15
y= -1 

therefore x=7 and y= -1
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There are 9 quilts with 18 yards . How many yards would be required for 10
pychu [463]
Hello!

First, you set up a proportion : quilts / yards = 9 / 18 = 10 / x
Then, you solve for x.

x = 20


Hope this helps! If you have any further concerns, feel free to let me know!

8 0
3 years ago
Diana bought a car for $5000 and plans to sell it to make a 20% profit. What should she sell it for to make the profit she desir
nalin [4]
You need to know 20% of $5000.  "Of" means "times".  

$5000 x 0.20 (which is 20% written as a decimal)

=$1000 profit she wants to make

$5000 (original price) + $1000 (profit) = $6000 (sale price)
4 0
3 years ago
Read 2 more answers
The equation C = 5 9 F − 160 9 gives the relation between temperature readings in Celsius and Fahrenheit.
Pavel [41]

Step-by-step explanation:

The question is wrong. The correct equation is :

C=\frac{5}{9}F-\frac{160}{9}

We know that the equation gives the relation  between temperature readings in Celsius and Fahrenheit.

Therefore, giving that we know the value in Fahrenheit ''F'' we can find the reading in Celsius ''C''. This define a function C(F) that depends of the variable ''F''.

So for the incise (a) we answer Yes, C is a function of F.

For (b) we need to find the mathematical domain of this function. Giving that we haven't got any mathematical restriction, the mathematical domain of the function are all real numbers.

Dom (C) = ( - ∞ , + ∞)

For (c) we know that the water in liquid state and at normal atmospheric pressure exists between 0 and 100 Celsius.

Therefore the range will be

Rang (C) = (0,100)

Now, we need to find the domain for this range. We do this by equaliting and finding the value for the variable ''F'' :

For C = 0 :

0=\frac{5}{9}F-\frac{160}{9} ⇒ F=32

And for C = 100 :

100=\frac{5}{9}F-\frac{160}{9} ⇒ F=212

Therefore, the domain as relating temperatures of water in its liquid state is

Dom (C) = (32,212)

For (d) we only need to replace in the equation by F=71 and find the value of C ⇒

C=\frac{5}{9}F-\frac{160}{9} ⇒

C=(\frac{5}{9})(71)-\frac{160}{9}

C=\frac{65}{3} ≅ 21.67

C(71) = 21.67 °C

4 0
3 years ago
Tim predicts he will get 98 points on the next exam. If Tim actually earned 62 points, what was Tim's percent error? Round your
zloy xaker [14]
% change= (new # - original #) ÷ original # x 100

original #= 98
new #= 62

% change= (62-98)/98 x 100
= -36/98 x 100
= -0.36734 x 100
= -36.73%

Rounded to nearest 10th of %= -36.7%

CHECK:
= 98 - (98 * 36.73%)
= 98 - (98 * 0.3673)
= 98 - 36
= 62 new #

ANSWER:
Her percent error was 36.7% (rounded to the nearest tenth of a percent). The negative indicates a decrease.

Hope this helps! :)
5 0
3 years ago
Read 2 more answers
What is the quadrant of (-4,9)
IRISSAK [1]
2. -4 goes over left and 9 goes up. q1 is top right, q2 is top left, q3 is bottom left, q4 is bottom right.
5 0
4 years ago
Read 2 more answers
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