Answer:
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.
