найдите сумму -5/6+(-7/8) -6 7/15+(-8 3/10)

1)5 7/8 + 6 3/10 = 5 35/40 + 6 12/40 = 11 47/40 = 12 7/402) 6 3/8 + 2 5/9 = 6 27/72 + 2 40/72 = 8 67/423) 1 8/21 + 4 3/14 + 2 2/7 = 1 16/42 + 4 9/42 + 2 12/42 = 7 37/42