Решите выражегие (3целых1/2-2целых2/3+5 целых5/6+4целых3/5): 21

(3 1/2 - 2 2/3 + 5 5/6 + 4 3/5) : 21 = 169/315
1) 3 1/2 - 2 2/3 = 3 3/6 - 2 4/6 = 2 9/6 - 2 4/6 = 5/6
2) 5/6 + 5 5/6 = 5 10/6 = 5 5/3 = 6 2/3
3) 6 2/3 + 4 3/5 = 6 10/15 + 4 9/15 = 10 19/15 = 11 4/15
4) 11 4/15 : 21 = 169/15 * 1/21 = 169/315