2)6/7 + 3/11 - 1
3)(6/15 + 2/3)+(1/4 + 1/5)

6/7 + 3/11 - 1 = 66/77 + 21/77 - 1 = 87/77 - 1 = 1 10/17 - 1 = 10/17(6/15 + 2/3)+(1/4 + 1/5) = 1 31/601) 6/15 + 2/3 = 6/15 + 10/15= 16/15 = 1 1/152)1/4+1/5 = 5/20 + 4/20 = 9/203)1 1/15 + 9/20= 1 4/60 + 27/60 = 1 31/60