question: James gets 80 emails a day.  20% of those emails don't require any response.  He responds to the rest of them.  How many emails does he respond to in a 5 day work week?
answer: He gets 80*.2=<<80*.2=16>>16 emails he doesn't need to respond to
  So he responds to 80-16=<<80-16=64>>64 emails
  So he responds to 64*5=<<64*5=320>>320 emails a week
  #### 320