Question

6) We ordered music CDs. Ted ordered 5 rock CDs and 4 hip hop CDs for a total of $120. From the same site, Betty ordered 3 rock CDs and 5 hip hop CDs for a total of $98.

a) Write the system of 2 linear equations.
b) How much did each rock CD cost if each rock CD was the same price?
c) How much did each hip hop CD cost if each hip hop CD was the same price?
-show work-

Answer 1

A) 5x + 4y = 120

3x + 5y = 98

B) To solve this, we must solve the equation.

5x + 4y = 120

3x + 5y = 98

STEP ONE:

Divide

x + 4/5y = 24

STEP TWO:

Substitute the variable

x = 24 - 4/5y

STEP THREE:

Substitute the value of the variable

3(24 - 4/5y) + 5y = 98

STEP FOUR:

Multiply

72 - 12/5y + 5y = 98

STEP FIVE:

Subtract 72 from both sides

-12/5y + 5y = 26

STEP SIX:

Add

Turn 5y into 25/5y

-12/5y + 25/5y = 26

13/5y = 26

2.6y = 26

STEP SIX:

Divide 2.6 from both sides

26/2.6 = 10

y = 10

Each Hip-Hop CD Costs $10

(We will save this for later, because the question asked about rock CDs.)

STEP SEVEN:

Find x

x = 24 - 4/5(10)

4/5 = 0.8

0.8(10) = 8

x = 24 - 8

x = 16

Therefore, each Rock CD costed $16.

C) We found this earlier, each Hip-Hop CD costs $10.

Sorry this was a little lengthy, but I hope this helped!