a) 8 1/6 : 2 1/3 = 49/6 : 7/3 = (49/6) * (3/7) = 147/42 = 7/2 = 3.5

б) (2,5 + 3)^2 = (5.5)^2 = 30.25

в) 3 3/4 - 1,25 = 15/4 - 5/4 = 10/4 = 2.5