Three friends share a large pizza. Maria eats 1/4 of the pizza, and Ahmed eats 3/8 of the pizza. How much is left for the third person? Express your answer in simplest form.

Maria and Ahmed eat 1/4 + 3/8 = 2/8 + 3/8 = 5/8 of the pizza.

This means there is 1 - 5/8 = 8/8 - 5/8 = 3/8 of the pizza left for the third person. Answer: \boxed{\frac{3}{8}}.