How to figúrate out if x makes the equation true

You plug in the number for x and if it is equal to the solution then it is correct

Someone already explained this and their right but I wanted to add an example.

Lets say you have the equation 4x+3=19.

You solve it by subtracting three from both sides to isolate x which gives you 4x=16 and dividing both sides by 4 to get you an answer of 4.

Now, you know x=4 but you're not completely sure so you can check it.

Substitute the known value of x into the original equation and check to see if both sides equal.

4 (4) + 3=19

16+3=19

19=19

This checks out so your answer is correct.