Hm. I got a different answer.
Turn the mixed number into an improper fraction. So 6 3/4 becomes 27/4.
Multiply each side by the reciprocal of (5/8) to solve for m.
(8/5)(5/8)m=(27/4)(8/5)
(8/5)(5/8) cancel each other out.
You are left with m= 216/20
This reduces to 54/5
54/5= 10.8
So m=10.8
Using substitution,
(5/8)(10.8)=6.75
6.75=6.75