12-(х+4целых 7/15) = 5 целых 13/15
X + 4 7\15 = 12 - 5 13\15 X + 4 7\15 = 11 15\15 - 5 13\15 = 6 2\15 X = 6 2\15 - 4 7\15 = 5 17\15 - 4 7\15 = 1 10\15 = 1 2\3