The local animal shelter is taking care of three puppies. They need to feed each puppy two cups of food a day. Each bag of dog food contains 36 cups of food. How many bags of dog food will they need to feed all the puppies for a whole week?
a. Using a variable, write the equation(s) used to solve the problem:
b. Write your answer as a whole number.
c. How many cups of food are left in the bag of dog food for the next week?
d. Show how your answer makes sense using estimation.