Question

at a particular music store CDs are on sale at $15 for the first one purchased and $11 for each additional this purchased maria spent $70 on CDs how many CDs has Mariah purchase

Answer 1

 $15 <--- First CD
 $11
 $11
 $11
 $11
 $11
+-------
$70: A total of 6 CDs

Answer 2

y = 11x + 15.....x = CD's purchased....y = total cost

70 = 11x + 15
70 - 15 = 11x
55 = 11x
55/11 = x
5 = x.....so she purchased 5 CD's