First, give them the same denominator. The easiest way to do this in this case is multiply both the numerator and denominator of 5 / 2 by 2.
5/2 * 2/2 = 10/4
Then, to find how many sets of bowls you can make, divide by 3 / 4.
(10/4)/(3/4) = 3 and 1/3.
You can't have a third of a set, so the amount of full sets Alexandra can make is 3.