Kenny earns $525 because 35 x 15 = <<35*15=525>>525
He spends $225 on video games because 5 x 45 = <<5*45=225>>225
He has $300 left because 525 - 225 = <<525-225=300>>300
He can buy 60 books because 300 / 5 = <<300/5=60>>60
#### 60