Give the step-by-step reasoning process and then the final answer. If there are 8 slices in a large pizza, how many slices will remain if Mary orders 2 large pizzas and eats 7 slices?
The number of total slices of pizza is 8 slices per pizza * 2 large pizzas = 16 slices. If Mary eats 7 slices, then 16 - 7 = 9 remain.
The final answer: 9.