Students in 6 classes at the same ratio of cheese pizza slices to pepperoni slices. If the ratio is 2:5 and the total number of pizza slices is 2.1, how many pizzas of each type did the students eat?
There are some gaps in your question:
I will take the total number of slices to be 21, not 2.1
2 / [2+5] x 21 = 6 slices of cheese pizzas.
5 / [2+5] x 21 = 15 slices of pepperoni pizzas.
We can't tell "how many pizzas of each type did the students eat", because we don't know how many slices was each pizza sliced into, because you don't give that information.
