John buys game loot boxes for $5 each.  The average value of items inside is $3.5.   He spends $40 on loot boxes.  What is the average amount he lost?
He bought 40/5=<T>divide(40, 5)=8.0 boxes
He loses an average of 5-3.5=$<T>subtract(5, 3.5)=1.5 per box
So he loses an average of 1.5*8=$<T>multiply(1.5, 8)=12.0
