(7 14/45:7-39/40)×7,2

Решение:1) 7 14/45 : 7 = 329/45 : 7/1 = 329/45 * 1/7 = 47/45;2) (47/45 - 39/40) * 7,2 = 47/45 * 7,2 - 39/40 * 7,2;3) 47/45 * 7,2 = 47/45 * 7 2/10 = 47/45 * 72/10 = 47/5 * 8/10 = 376/50;4) -39/40 * 7/2 = -39/40 * 7 2/10 = -39/40 * 72/10 = -39/5 * 9/10 = -351/50;5) 376/50 - 351/50 = 25/50 = 1/2 = 0,5.Ответ: 1/2 или 0,5.