5/6 - 0,75 = 4/6 - 3/4 = 1/6

1/6 + 0'4 = 1/6 + 0.4 = 1/6 + 2/5 = 7/30

1/4 + 1,1 = 1/4 + 1.1 = 1/4 + 11/10 = 3/4