Question

You are packing for a picnic. You make tuna sandwiches, which use 2 slices of bread, and club sandwiches, which use 3 slices of bread. You have a total of 21 sandwiches that used a total of 58 slices of bread. How many club sandwiches did you make?

Answer 1

Answer: you made 5 tuna sandwiches and 16 club sandwiches.

Explanation:

Let x represent the number of tuna sandwiches that you made.

Let y represent the number of club sandwiches that you made.

You have a total of 21 sandwiches. This means that

x + y = 21

You make tuna sandwiches, which use 2 slices of bread, and club sandwiches, which use 3 slices of bread. You used a total of 58 slices of bread. This means that

2x + 3y = 58 - - - - - - - - - - - -1

Substituting x = 21 - y into equation 1, it becomes

2(21 - y) + 3y = 58

42 - 2y + 3y = 58

- 2y + 3y = 58 - 42

y = 16

x = 21 - y = 21 - 16

x = 5