Given the task definition and input, reply with output. You are provided with an arithmetic question. Your task is to compute the solution using the given arithmetic operations. The only arithmetic operators needed to answer the questions are'+'(addition) and'-'(subtraction). The answer should be correct to one decimal place.

Joan found 79 seashells on the beach, she gave Mike 63 of theseashells. How many seashells does she now have?

16.0