We'll discuss the steps solving an example:
4x - 2x + 5 = 7
We'll combine like terms to put the equation into the standard form ax + b = 0.
2x + 5 = 7
We'll subtract 5 both sides, to isolate x to the left side:
2x + 5 - 5 = 7 - 5
2x = 2
We'll divide by 2 both sides:
x = 1
The solution of the equation is x = 1.
Comparing, we can solve the general example ax + b = 0.
ax = -b
x =-b/a is the only solution of the equation. b has to be different from zero, for the solution to exist.