Thomas buys a weight vest.  It weighed 60 pounds and worked well for him in the beginning but after a bit of training he decides he wants to increase the weight by 60%.  The weights come in 2-pound steel ingots.  Each ingot cost $5 and if you buy more than 10 you get a 20% discount.  How much does it cost to get the weight he needs?
He needs to buy 60*.6=<T>multiply(60, 0.6)=36.0 pounds
So he needs to buy 36/2=<T>divide(36, 2)=18.0 weight plates
That would cost 18*5=$<T>multiply(18, 5)=90
Since he bought more than 10 he gets a discount so he gets 90*.2=$<T>multiply(90, 0.2)=18.0 off.
That means he paid 90-18=$<T>subtract(90, 18)=72
