This exercise is asking you to find the value of x or solve for x, to do so you have to isolate or leave x alone by doing different mathematical operations according to the given equation.
The given equation is 4x-3x+4x=20, which is a two step equation meaning that in order to solve for x you need to do two different mathematical operations.
4x-3x+4x=20 Combine like terms
5x=20 Divide in both sides by 5 to isolate x
x=4
The value of x in this equation is 4.