The answer to this question is 4 5/8.
1. Change to fractions.
7 3/4 becomes 31/4 and 3 1/8 becomes 25/8.
2. Find the Least Common Denominator (8).
31/4 * 2/2 becomes 62/8
3. Subtract the two fractions
62/8 - 25/8 = 37/8
4. Turn the fraction back into a mixed number.
37/8 = 4 5/8
4 5/8 is the answer.