5\8 m -7\12 m +5\6 m =1\4
5/8m-7/12m+5/6m=1/4 15/24m- 14/24m+20/24m=6/24 21/24m=6/24 m=6/21
12/7+5/6=5/8-1/4+5/6=9/9