Answer :

4m + 9 + 5m - 12 = 42

9m - 3 = 42
      +3      +3
9m = 45
/9        /9

m = 5
olemakpadu
4m + 9 + 5m - 12 = 42

4m + 5m = 42 - 9 + 12

9m = 45

m = 45/9

m = 5