Given
x + 4 + 2x = x + 20
First collect like terms
x + 2x - x = 20 - 4
2x = 16
Next, divide through by 2
x = 16/2
x = 8
To check your answer, substitute 8 as x in the equation.
If both side of the equation are equal, hence, the solution is x = 8.
x + 4 + 2x = x + 20
8 + 4 + 2(8) = 8 + 20
8 + 4 + 16 = 28
28 = 28
Hence, x = 8
Final answer
x = 8
