A store gives a 10% discount for the amount of the sell that was over $1000.  John buys 7 items that each cost $200.  What does his order cost after the discount?
His order came out to 7*200=$<T>multiply(7, 200)=1400
So there was 1400-1000=$<T>subtract(1400, 1000)=400 that qualified for the discount
So his discount saved 400*.1=$<T>multiply(400, 0.1)=40.0
So his purchase came out to 1400-40=$<T>subtract(1400, 40)=1360
