What is the difference of one and a half and three fourths?

This is subtraction of fractions.

1 1/2 - 3/4

Convert to improper fractions

3/2 - 3/4

Convert to an equivalent fraction by multiplying the left hand fraction by '2'

6/4 - 3/4

Subtract the numertors(top)

6 - 3 = 3

Hence answer is 3/4