Предварительно сократив дроби,найдите значение выражения : 3/12+25/30, 10/24-21/54, 30/54+22/30, 28/40-10/75, 12/27+14/21,

3/12 + 25/30 = 1/4 + 5/6 = (1 * 6 + 5 * 4)/24 = (6 + 20)/24 = 26/24 = 13/12 = 1 1/12;10/24 - 21/54 = 5/12 - 7/18 = (5 * 3 - 7 * 2)/36 = (15 - 14)/36 = 1/36;30/54 + 22/30 = 5/9 + 11/15 = (5 * 5 + 11 * 3)/45 = (25 + 33)/45 = 58/45 = 1 13/45;28/40 - 10/75 = 7/10 - 2/15 = (7 * 3 - 2 * 2)/30 = (21 - 4)/30 = 17/30;12/27 + 14/21 = 4/9 + 2/3 = (4 * 1 + 2 * 3)/9 = (4 + 6)/9 = 10/9 = 1 1/9;14/24 - 15/40 = 7/12 - 3/8 = (7 * 2 - 3 * 3)/24 = (14 - 9)/24 = 5/24;12/18 - 5/60 = 2/3 - 1/12 = (2 * 4 - 1 * 1)/12 = (8 - 1)/12 = 7/12;4/24 + 3/36 = 1/6 + 1/12 = (1 * 2 + 1 * 1)/12 = (2 + 1)/12 = 3/12 = 1/4.