To find out how much of the pizza the Mendes family ate on Saturday, we need to look at what they had left over and how much they ate.
Initially, they had 49 slices of pizza left over from Friday. On Saturday, they ate 34 slices for lunch.
Therefore, the amount of pizza the Mendes family ate on Saturday is:
34 slices
So, the Mendes family ate 34 slices of pizza on Saturday.