Joan is preparing sandwiches for a family potluck. She decides to make ham sandwiches and grilled cheese sandwiches. One ham sandwich requires 2 slices of cheese, and one grilled cheese sandwich requires 3 slices of cheese. She uses a total of 50 slices of cheese to make the sandwiches. If she makes 10 ham sandwiches, how many grilled cheese sandwiches does she make? Give me reasons, before answering the question
The number of cheese slices used to make the ham sandwiches is 10 * 2 = 20 cheese slices. The number of cheese slices used to make the grilled cheese sandwiches is 50 - 20 = 30 cheese slices. The number of grilled cheese sandwiches she makes is 30 / 3 = 10 grilled cheese sandwiches. So the final answer is 10.