6 5/12×16/21=77/12*16/21

6 512 х 1621= 7712 х 1621
6 512 х 1621 = 7712 х 1621 = 8818= 4 1618 = 4 89
7712 х 1621= 8818 = 4 1618 = 4 89
4 89 = 4 89