What is 5x - 5 = x + 15

Question

Please show me the simplest way!!!

Answer 1

An equation (like 5x - 5 = x + 15) is like a teeter-totter with the equal sign as the balance between the left side and the right side. You MUST keep everything balanced so anything you do to the left side, you must also do the the right side.

Solving this equation will ultimately (when you are finished) look like x = (some number) so what you would like to do is get all the x's on the left side and all the numbers on the right side. So, what if you subtract x from the right side? That will mean the right side will be "x - x + 15" or, since "x - x" = 0 you'll just have 15. But, like I mentioned, you must do the same thing to both sides of the equation. So, also subtract x from the left side of the equation. That will mean the left side will be "5x - x - 5" or, since "5x - x" is 4x, it will be "4x - 5".

So now you have: 4x - 5 = 15

Now, what if you add 5 to both sides of the equation. The left side will be "4x - 5 + 5" or just "4x" and the right side will be "15 + 5" or "20".

So you have: 4x = 20

Now, what if you divide both sides by 4? The left side will be 4x/4 or "x" and the right side will be 20/4 or 5.

So you will have: x = 5.

And you solved the problem!