Answer:
m = 5
Explaination:
Given equation is :
4m + 9 + 5m - 12=42
We need to solve this, We see that given equation is linear equation
So, we simplify the left hand side
4m + 9 + 5m - 12=42
Combine like terms
here 4m & 5m are like terms
4m + 5m + 9-12 = 42
9m + 9 - 12 = 42
9m + -3 = 42
Now move -3 to right side
9m = 42 + 3
9m = 45
m = 5