2 / 5 × 4 / 5 = 5 / 7-9 / 5 × 7 / 5 = 3 / 87 × 86 (1 / 5 + 2 / 3) × 15 = 1 / 2 × 15 / 1 + 1 / 3 × 2 / 1 = 5 / 6 × 9 / 5 + 9 / 5 × 6 / 1 = (to do process,)

(1 / 5 + 2 / 3) × 15 = 1 / 5 * 15 + 2 / 3 * 15 = 3 + 10 = 13
1 / 2 × 15 / 1 + 1 / 2 / 3 = 1 / 2 (1 / 15 + 1 / 3) = 1 / 2 * 2 / 5 = 1 / 5
5 / 6 × 9 / 5 + 9 / 5 × 6 / 1 = 5 / 9 (5 / 6 + 1 / 6) = 5 / 9
This is the simplest content of fraction multiplication. Listening to three minutes of homework in class will save half an hour