А) - 7/15 + 4 / 15 = - 3/15 = - 1/5
б) - 17/21 - 5/21 = - 22/21 = 1 1/21
в) 15/22 + (- 7/22) = 8/22 = 4/11
г) - 4/5 - 1/3 = - 12/15 - 5/15 = - 17/15 = - 1 2/15
д) 3/4 + (- 1/3) = 3/4 - 1/3 = 9/12 - 4/12 = 5/12
е) - 4/5 - (- 3/4) = - 4/5 + 3/4 = -16/20 + 15/20 = - 1/20
ж) 3/4 - (- 4/9) = 3/4 + 4/9 = 27/36 + 16/36 = 43/36 = 1 7/36
з) - 9/14 - 2/7 = - 9/14 - 4/14 = - 13/14