Выполните сложение: а) 3/10 + 4/10; б) 1/2 + 1/2; в) 3/7 + 5/7; г) 12/31 + 18/31; д) 2/3 + 3/3; е) 4/5 + 1/5 + 2/5

а) 3/10 + 4/10 = (3+4)/10 = 7/10; б) 1/2 + 1/2 = (1+1)/2 = 2/2 = 1; в) 3/7 + 5/7 = (3+5)/7 = 8/7; г) 12/31 + 18/31 = (12+18)/31 = 30/31; д) 2/3 + 3/3 = (2+3)/3 = 5/3; е) 4/5 + 1/5 + 2/5 = (4+1+2)/5 = 7/5