Peyton has 2 pizzas. Each pizza is cut into 10 equal slices. She and her friends eat 14 slices. What part of the pizzas they eat?

Well, each pizza is cut into 10 slices, that means both pizzas are 10+10 slices, or 20 slices, then they ate 14 of those 20 slices.

so they ate 14 out of 20, or 14/20, which simplifies to 7/10.