а) 5/24 + 3/8 = (5*1 + 3*3)/24 = 14/24 = 7/12; б) 7/10 - 2/5 = (7*1 - 2*2)/10 = 3/10; в) 7/9 - 5/7 = (7*7 - 5*9)/63 = 4/63; г) 2/3 + 7/8 = (2*8 + 7*3)/24 = 37/24 = 1 13/24; д) 3/4 - 1/6 = (3*3 - 1*2)/6 = 1/6; е) 5/6 + 1/9 = (5*3 + 1*2)/18 = 17/18 ; ж) 8/25 + 17/20 = (8*4 + 17*5)/100 = 117/100 = 1 17/100; з) 4/45 - 1/30 = (4*2 - 1*3)/90 = 5/90 = 1/18; и) 17/18 - 11/12 = (17*2 - 11*3)/36 = 1/36; к) 11/15 + 5/12 = (11*4 + 5*5)/60 = 69/60 = 23/20 = 1 3/20; л) 1/3 + 1/6 = (1*2 + 1*1)/6 = 3/6 = 1/2; м) 3/4 - 2/5 = (3*5 - 4*2)/20 = 7/20.