Question

You and a friend bought the same number of CDs and the same number of DVDs at two different stores. Your store charges $6 per CD, $9 per DVD, and you paid $36. Your friends store charges $7 per CD, $8 per DVD, and he paid $37. How many CDs did you buy?

Answer 1

Let the number of CDs be x and the number of DVDs be y.
6x+9y=36-(1)
7x+8y=37-(2)
(1)*7=>
42x+63y=252-(3)
(2)*6=>
42x+48y=222-(4)
(3)-(4)=>
15y=30
y=30/15
y=2
Substitute the value of y in (1) to find x.

Answer 2

Ohh that helps thanks!

Answer 3

yw.:)