Write four different equation with -3 as solution.
5x + 20 = 5 subtract 20 both sides
5x = 5 - 20
5x = -15 divide by 5 both sides
x = -15/5
x = -3
3x - 6 = -3x - 24 add 3x both sides
3x + 3x - 6 = - 24
6x - 6 = -24 add 6 both sides
6x = -24 + 6
6x = -18 divide by 6 both sides
x = -18/6
x = -3
1/3 x + 10 = 9 subtract 10 both sides
1/3 x = 9 -10
1/3 x = - 1 multiply by 3 both sides
x = -1(3)
x = -3
x + 23 = 20 subtract 23 both sides
x = 20 - 23
x = -3
In all previous procedures you constructed the equation by taking into account that x=-3, that is the key to determine the expressions left side and right side. For example in the last procedure for x + 23 = 20, you know that -3 plus 20 is equal to 20.