As you can see:
RM+MT = RT
Where:
RM = 5x + 9
MT = 8x - 6
RT = 198
Replacing the data:
5x + 9 + 8x - 6 = 198
Add like terms:
(5x + 8x) + (9 - 6) = 198
13x + 3 = 198
Solve for x:
Subtract 3 from both sides:
13x + 3 - 3 = 198 - 3
13x = 195
Divide both sides by 13:
13x/13 = 195/13
x = 15
