how do you solve this

Question

Ari spent $525 buying some CDs in a sale. He bought some rock CDs for $20 each and some blues CDs for $5 each. Ari bought five times as many rock CDs as blues CDs.

Answer 1

b = number of blues CDs at $5 each

5b = number of rock CDs at $20 each

 

($5)b + ($20)(5b) = $525

 

5b + 100b = 525

 

b = 525/105 = 5

5b = 5(5) = 25