question: Mark's car breaks down and he needs to get a new radiator.  The cost for a new radiator is $400 but he goes to get it at a junk shop and gets it for 80% off.  He then hires a mechanic to install it and it takes 3 hours at $50 an hour.  How much did he pay?
answer: The discount on the radiator was 400*.8=$<<400*.8=320>>320
  So he paid 400-320=$<<400-320=80>>80
  The mechanic charges 3*50=$<<3*50=150>>150
  So in total he paid 80+150=$<<80+150=230>>230
  #### 230