3 7/8 + 4 5/12 (сложение и вычитание смешанных чисел).

3 7/8 + 4 5/12 = 3 + 4 + 7/8 + 5/12 = 7 + (7 * 3) / (8 * 3) + (5 * 2) / (12 * 2) = 7 + 21/24 + 10/24 = 7 + (21 + 10) / 24 = 7 + 31/24 = 7 + 1 (31 - 1 * 24) / 24 = 7 + 1 (31 - 24) / 24 = 7 + 1 7/24 = 7 + 1 + 7/24 = 8 + 7/24 = 8 7/24.

Решим подобные примеры:

1) 4 2/9 - 3 8/27 = 4 - 3 + 2/9 - 8/27 = 1 + (2 * 3) / (9 * 3) - 8/27 = 1 + 6/27 - 8/27 = 1 + (6 - 8) / 27 = 1 - 2/27 = 27/27 - 2/27 = (27 - 2) / 27 = 25/27;

2) 3 3/5 + 2 2/10 = 3 + 2 + 3/5 + 2/10 = 5 + (3 * 2) / (5 * 2) + 2/10 = 5 + 6/10 + 2/10 = 5 + (6 + 2) / 10 = 5 + 8/10 = 5 + (4 * 2) / (2 * 5) = 5 4/5.