Ask your teacher if you could complete any extra-credit assignments. You could also ask your teacher why you're failing and potentially get help with what you're struggling on. A lot of people fail because they never study, so also do plenty of that!
The answer is any value that you put in for x would make the equation true. When you simplify the whole equation it looks like this: 2x - 6 = 2x - 6, therefor you could replace x with any value.
