1. 7/20*15/17 = 15/20*7/17 = 3/4*7/17 = 21/68
2. 16/15 ÷ 8/25 = 16/15 × 25/8 = (16 ÷ 8)/(15 ÷ 5) × (25 ÷ 5)/(8 ÷ 8) = 2/3 × 5/1 = (2 × 5)/(1 × 3) = 10/3 = 3 1/3
3. (3/4)3 × (4/3)3 = 2.25 + 4 = 6.25
1. 7/20*15/17 = 15/20*7/17 = 3/4*7/17 = 21/68
2. 16/15 ÷ 8/25 = 16/15 × 25/8 = (16 ÷ 8)/(15 ÷ 5) × (25 ÷ 5)/(8 ÷ 8) = 2/3 × 5/1 = (2 × 5)/(1 × 3) = 10/3 = 3 1/3
3. (3/4)3 × (4/3)3 = 2.25 + 4 = 6.25