Решите уравнение. (4 8/21+z)-7 13/21=2 12/21
4 8/21 + z = 2 12/21 + 7 13/21 4 8/21 + z = 9 25/21 = 10 4/21 z = 10 4/21 - 4 8/21 = 9 25/21 - 4 8/21 z = 1 17/21
4 8/21+z=2 12/21+7 13/21 z=10 4/21-4 8/21 z=5 17/21