А=m-6 1/2
если А=6 3/4,то 6 3/4=m-6 1/2
...........................m-6 1/2=6 3/4
...........................m= 6 3/4 + 6 1/2
...........................m=6 3/4+6 2/4
...........................m=13 1/4
...........................m=13.25
если А=3 5/8, то 3 5/8=m-6 1/2
............................m-6 1/2=3 5/8
............................m=3 5/8+6 1/2
............................m=3 5/8+6 4/8
............................m=10 1/8
если А=0, то 0=m-6 1/2
......................m-6 1/2=0
......................m=6 1/2
......................m=6.5