James visits 20 houses to try and make a sale.  He manages to sell something in every house.  The next day he visits twice as many houses but only sold to 80% of houses.  If he sold two things at each house in each of the two days, how many items did he sell?
The second day he visited 20*2=<T>multiply(20, 2)=40 houses
So he sold things at 40*.8=<T>multiply(40, 0.8)=32.0 houses
So in total he sold things at 20+32=<T>add(20, 32)=52 houses
That means he sold 52*2=<T>multiply(52, 2)=104 things
