Some friends went to the Regal Movie Theater and bought three small buckets of popcorn and six boxes of candy. The total for all the food snacks was $54. The last time you were at the theater, you bought a small bucket of popcorn and a box of candy and paid $13. Write a system of equations to represent the situation, using x. to represent the cost of a box of candy and using y to represent the cost of a bucket of popcorn.