1. (1 - 3/7) + 1 3/7 = 4/7 + 1 3/7 = 2

2. (5 - 3/4) - (2 1/4 + 1 3/4) = 4 1/4 - 4 = 1/4 = 0,25

3. (5/11 + 6/11) - (1 - 6/11) = ( -1/11) - 5/11 = ( -6/11) (= 0,(09)1)