Решите пж
а) 1/2 - 1/4 + 2/5
б) 3/4 - 1/2 + 7/8
в) 5/6 - 2/3 + 1/4

1/2 - 1/4 + 2/5 = 10/20 - 5/20 + 8/20 = 13/203/4 - 1/2 +7/8 = 6/8 - 4/8 + 7/8 = 9/8 = 1 1/85/6 - 2/3 + 1/4 = 10/12 - 8/12 + 3/12 = 5/12