what 2 equations do i need to set this up

Question

A store is selling CDs for $10.50 an $8.50. You can buy 10 disks and spend a total of $93. How many CDs did you buy that cost $10.50 and which cost $8.50

Answer 1

Let x = the number of CDs that cost $10.50.  Since you bought 10 CDs in total, the number that cost $8.50 is 10-x.

 

$93 = ($10.50)*x + ($8.50)*(10-x)

 

Solve for x.