Решите примеры a) 1/12+3/4 = б) 3 целых 1/2+1/3 = в) 2/3-1/5 = г) 1 целая 1/5-3/4=

a) 1 / 12 + 3 / 4 = (12 / 12 * 1 + 12 / 4 * 3) / 12 = (1 * 1 + 3 * 3) / 12 = (1 + 9) / 12 = 10 / 12 = 5 * 2 / (2 * 6) = 5 * 1 / (1 * 6) = 5 / 6;

б) 3 целых 1 / 2 + 1 / 3 = 3 + 1 / 2 + 1 / 3 = 3 + (1 * 3 + 1 * 2) / 6 = 3 + (3 + 2) / 6 = 3 + 5 / 6 = 3 целых 5 / 6;

в) 2 / 3 - 1 / 5 = (15 / 3 * 2 - 15 / 5 * 1) / 15 = (5 * 2 - 3 * 1) / 15 = (10 - 3) / 15 = 7 / 15;

г) 1 целая 1 / 5 - 3 / 4 = 1 + 1 / 5 - 3 / 4 = (1 * 20 + 1 * 4 - 3 * 5) / 20 = (20 + 4 - 15) / 20 = (5 + 4) / 20 = 9 / 20.