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
valentina_108 [34]
3 years ago
11

Mrs Tan bought 4 times as many pens as notebooks and each notebook cost $8.20 more than each pen. She spent $26 more on the book

s than the pens. Mrs Tan spent $394 altogether on the pond and notebooks, how much was the cost of a notebook?
Mathematics
1 answer:
lilavasa [31]3 years ago
8 0
Let x be the cost of 1 pen
then cost of 1 notebook = x + 8.20

Let y be the number of pens Tan buys
then number of notebooks Tan buys = y/4

She spent $26 more on books than on pens which means

Cost of notebooks - Cost of pens = 26
(x + 8.20) * y/4 - xy = 26

Sinplifying it

(xy + 8.20y)/4 - xy = 26
(xy + 8.20y - 4xy)/4 = 26
8.20y - 3xy = 104

She spent $394 which means

Cost of notebooks + Cost of pens = 394
(x + 8.20) * y/4 + xy = 394

Simplifying it

(xy + 8.20y)/4 + xy = 394
(xy + 8.20y + 4xy)/4 = 394
8.20y + 5xy = 1576

Now, we have two equations,

(1) 8.20y - 3xy = 104
(2) 8.20y + 5xy = 1576

Now we need to find a third equation with either x or y as the subject of any of both the previous equations.

Let's make y the subject of (2) equation

8.20y + 5xy = 1576
y(8.20 + 5X) = 1576
(3) y = 1576/(8.20 + 5x)

Let's substitute the new value of y from (3) into (1) because we rearranged (2) to from (3)

8.20y - 3xy = 104
y(8.20 - 3x) = 104
y = 104/(8.20 - 3x)
1576/(8.20 + 5x) = 104/(8.20 - 3x)
1576 * (8.20 - 3x) = 104 * (8.20 + 5x)
12923.2 - 4728x = 852.8 + 520x
12923.2 - 852.8 = 4728x + 520x
12070.4 = 5248x
12070.4/5248 = x
x = 2.3

Now find the value of y by substituting the value of x in either equation, preferably (3)

y = 1576/(8.20 + 5x)
y = 1576/(8.20 + 5 * (2.3))
y = 80

Therefore cost of 1 notebook = x + 8.20 = 2.3 + 8.20 = $10.50

You might be interested in
C.
Art [367]

Answer:

I got 1,800 hope this helps

6 0
2 years ago
Read 2 more answers
The cube of a number equals 36 times that number.find the number.​
labwork [276]
Answer
The answer is 36.
Explanation:
Let the unknown number be x

x^3=x*36
or, x^3/x=36
or, x^2=36
or, x=6
.•. x=36
4 0
3 years ago
Read 2 more answers
WILL MARK U AS BRAINLIEST PLZ HELP
torisob [31]

Answer:

2 inches

Step-by-step explanation:

2 x 1 = 2

could you heart my post and mark me ect.

7 0
3 years ago
What is negative times x plus 7
ValentinkaMS [17]
-.x+7
-x+7=0
-x=-7
x=7...

Not too sure because of the way you wrote the question but this is the interpretation i gave it.
3 0
3 years ago
Read 2 more answers
Solve for x: x/7 - 3 ≥ 8.
stellarik [79]

Answer:

x is more than or equal to 77

Step-by-step explanation:

5 0
3 years ago
Other questions:
  • If Mags (m) is 34 years old, how old is Vector (v)
    7·1 answer
  • Mr. Rivera can grade 8 math test in 10 minutes . What is the teacher's unit rate
    9·2 answers
  • I need help with this i am really bad at math
    9·1 answer
  • Write the equation of the function.
    12·1 answer
  • How many outcomes are there for the following experiments? List all the possible outcomes. a) Tossing a coin
    13·1 answer
  • Someone Help plz!!!!!!
    8·1 answer
  • If you have to drive 200 miles and someone drives 4/10 of the distance and some one else drives 20% what does the other person.
    9·1 answer
  • A part manufactured by plastic injection molding has a historical mean of 100 and a historical standard deviation of 8. Find the
    13·1 answer
  • write an equation to represent the total cost for a certain number of cans. Use "c" for cost and "n" for number of cans​
    9·1 answer
  • Simplify and solve step by step 4x -2x -20x + x
    13·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!