- 5/2 + 2/5 = 5 × 5/2 × 5 + 2 × 2/5 × 2 = 25/10 + 4/10 = 29/10
- 6/7 + 1/2 = 6 × 2/7 × 2 + 1 × 7/2 × 7 = 12/14 + 7/14 = 19/14
- 3/5 - 1/4 = 3 × 4/5 × 4 - 1 × 5/4 × 5 = 12/20 - 5/20 = 7/20
- 7/12 + 2/3 = 7/12 + 2 × 4/3 × 4 = 7/12 + 8/12 = 15/12= 5/4
- 10/3 - 1/6 = 10 × 2/3 × 2 - 1/6 = 20/6 - 1/6 = 19/6