3
Пошаговое объяснение:
1) 1. 1/2 - 2/5 = 1. 5/10 - 4/10 = 1. 1/10
2) 2. 3/4 : 1. 1/10 = 11/4 : 11/10 = 11/4 * 10/11 = 1/2 *5/1 = 5/2 = 2. 1/2
3) 3/4 + 5/6 = 9/12 + 10/12 = 19/12
4) 19/12 * 6/19 = 1/2 * 1/1 = 1/2
5) 2. 1/2 + 1/2 = 2. 2/2 = 3
