Question

Ruben bought six new books for his collection. This increased his collection by 12%. How many books did he have before his purchases?

Answer 1

 20. Let x represent the amount of books he had:
x + 6 = 1.12x

Subtract x from both sides:
6 = 0.12x

Divide both sides by 0.12; x = 50

28. $6 + 0.025*$6 = $6 + $0.15 = $6.15