turn 2 1/4 into an improper fraction: 2 1/4 = 9/4
now you have 9/4 divided by 3/4
to divide 2 fractions invert the 2nd fraction and multiply
so change 9/4 / 3/4 to 9/4 x 4/3
now multiply the 2 top numbers and then the 2 bottom numbers:
9 *4 = 36
4 * 3 = 12
so you have 36/12 which = 3
so 2 1/4 / 3/4 = 3