3) 5 - 6 3/4

1. Convert the mixed number to an improper fraction: 6 3/4 = 27/4.
2. Rewrite 5 as a fraction with a denominator of 4: 5 = 20/4.
3. Subtract the fractions: 20/4 - 27/4 = -7/4 = -1 3/4.