He needs to save up $100 because 14,600 - 14,500 = <<14600-14500=100>>100
He earned $60 off trips because 40 x 1.5 = <<40*1.5=60>>60
He earned $40 off groceries because 100 - 60 = <<100-60=40>>40
He delivered $800 in groceries because 40 / .05 = <<40/.05=800>>800
#### 800