1/2 -1/4+2/5= 3/4-1/2+7/8= 5/6-2/3+1/4= найдите значение выражение

1/2-1/4+2/5=12/20
5/6-2/3+1/4=10/24
3/4-1/2+7/8=18/16

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