Hi there!
x = 20 is NOT a solution to this equation.
In this equation, when we want to find our value of x, we must multiply both sides of the equation by 2. In the current situation our variable x is divided by 2. Therefore, if we want to find its value, we must do the opposite of dividing, which is multiplying.
We end up with the following:
Therefore, the only solution to this equation is x = 80 and we can now conclude that x = 20 is NOT a solution to this equation.
~ Hope this helps you!