How many teaspoons are in three cups?

There are 16 Tablespoons in 1 cup.

3 teaspoons are in a Tablespoon.

16 X 3 = 48 (number of teaspoons in 1 cup)

48 X 3 = 144 (number of teaspoons in 3 cups)

This is assuming we are speaking of the common T, t, and cup as used in the typical U.S. baking :)