James decides to sell 80% of his toys.  He bought them for $20 each and sells them for $30 each.  If he had 200 toys how much more money did he have compared to before he bought them?
He bought all the toys for 20*200=$<T>multiply(20, 200)=4000
He sold 200*.8=<T>multiply(200, 0.8)=160.0 toys
He made 160*30=$<T>multiply(160, 30)=4800 from selling them
So he profits 4800-4000=$<T>subtract(4800, 4000)=800 profit
