Answer: Renee and Sumi ate
of the pizza.
Step-by-step explanation: Given that Renee ate
of a pizza, and Sumi ate
of the same pizza.
We are to find the part of the pizza they ate in all.
The part of the pizza ate by both of them is equal to the sum of the fractions of the pizza ate by them.
Therefore, the part of the pizza ate by Renee and Sumi is given by

Thus, Renee and Sumi ate
of the pizza.