question: A cup of mushrooms weighs 100 grams and has 3 grams of protein.  If John eats 200 grams of mushrooms every day how many grams of protein does he get per week?
answer: He eats 200/100=<<200/100=2>>2 cups per day
  So that means he gets 2*3=<<6=6>>6 grams of protein per day
  So he gets 6*7=<<6*7=42>>42 grams of protein per week
  #### 42