John used to buy 4 coffees a day for $2 each.  They raised the price by 50% so he cut the number of coffees he drinks in half.  How much money does he save per day compared to what he used to spend?
He now buys 4/2=<T>divide(4, 2)=2.0 coffees
The new price is 2*.5=$<T>multiply(2, 0.5)=1.0 more than the old price
So he now pays 2+1=$<T>add(2, 1)=3 per coffee
So he spends 3*2=$<T>multiply(3, 2)=6
He used to spend 4*2=$<T>multiply(4, 2)=8
So he saves 8-6=$<T>subtract(8, 6)=2 per day
