вычислите 7/12-1/3/1/2-2/5

(7/12 - 1/3) / (1/2 - 2/5) = = (7/12 - 4/12) / (5/10 - 4/10) = = (3/12) / (1/10) = 3/12 * 10/1 = = 5/2 = 2 1/2