Question

Mark went to an electronic store, purchased 2 CDs and 6 DVDs, and spent $156. Antonio went to the same store, bought 1 CD and 9 DVDs, and spent $210. How much does each CD sell for at the store? $12

$15

$18

$22

Answer 1

A.12

Explanation:

Got it right on the test

Hope this helps :)

Answer 2

For the answer to the question above,
Let C be CD's
Let D be DVD's

2C + 6D = 156
C + 9D = 210

6D = 156 - 2C
3D = 78 - C

C + 9D = 210
C + 3(78 - C) = 210
C + 234 - 3C = 210
234 - 210 = 3C - C
24 = 2C
12 = C

The cost of one CD is $12, so the answer is a.