Выполните действия: а) 2/3+1/2; б) -2/3-4/5; в) 2/3-7/8; г) 5/7-1/3.

а)
2/3 + 1/2 = 4/6 + 3/6 = 7/6 = 1 1/6;
б)
-2/3 - 4/5 = -10/15 - 12/15 = -22/15 = - 1 7/15;
в)
2/3 - 7/8 = 16/24 - 21/24 = - 5/24;
г)
5/7 - 1/3 = 15/21 - 7/21 = 8/21