To solve for x, your first step is to get rid of the 150 by subtracting it from both sides so that you get:
4x+6x=210
Then, you add like things:
10x=210
Divide both sides by 10 so that you can isolate x:
x=21
Check:
4(21)+6(21)+150=360
84+126+150=360
360=360
The answer is x=21.
