Note that: EF + FG = EG
Plug in to corresponding places.
10x + 20 + 36 = 156
Simplify
10x + 56 = 156
Isolate the x. Note the equal sign. What you do to one side, you do to the other. Do the opposite of PEMDAS.
10x + 56 (-56) = 156 (-56)
10x = 156 - 56
10x = 100
10x/10 = 100/10
x = 10
10 is your answer for x
hope this helps