Tom charges a fee of $100 a day to search for an item for the first 5 days and then $60 per day for every day after that.  How much did it cost for him to look for an item for 10 days?
The first 5 days cost 5*100=$<T>multiply(5, 100)=500
He gets 10-5=<T>subtract(10, 5)=5 days on discount
He paid 5*60=$<T>multiply(5, 60)=300 at the discounted rate
So in total he pays 500+300=$<T>add(500, 300)=800
