А) 3/5+3/7+9/7*4/15 б) (7/8-1/6): 2/9*21/22

А) 3/5+3/7+9/7*4/15 = 1 13/35
9/7*4/15 = 12/353/5+3/7+12/35 = 21/35+15/35+12/35= 48/35 = 1 13/35

б) (7/8-1/6):2/9*21/22 = 3 39/176
7/8-1/6 = 21/24 - 3/24 = 18/24 = 3/4
3/4:2/9 = 3/4*9/2=27/8
27/8*21/22 = 567/176 = 3 39/176