He received 10 special bills because 25 - 15 = <<25-15=10>>10
He has 80% of them left because 100 - 20 = <<100-20=80>>80
He has 8 left because 10 x .8 = <<10*.8=8>>8
His parents will give her $12 for them because 8 x 1.5 = <<8*1.5=12>>12
#### 12