The equation has to be a true statement.
Start with a true statement: 8 = 8
Now add 4x to both sides: 4x + 8 = 4x + 8
It's still a true statement.
Factor the right side: 4x + 8 = 4 (x+2)
Subtract 3 from both sides: 4x + 5 = 4(x+2) - 3
There's an example of an equation with infinitely many solutions. To solve it, work the process we used to create it in reverse.