You may want to review multiplying, adding and subtracting fractions first.
Expressions (things with x in them) have the same problem as fractions — sometimes two different-looking expressions mean the same thing. So you need to learn to simplify them. With linear expressions, there are just three rules you need to learn. First, you can combine multiples of x. For example, 2x + 3x = 5x. Second, if an expression in parentheses is multiplied by a number, you have to multiply every term of the expression by that number. For example, −2(x − 1) = −2x + 2 (since −2 times −1 is 2). Finally, if you have a − sign before some parentheses, you can change it into a + sign if you take the negaitve of everything in the parentheses.
An example that combines all of these would be to simplify −(1 ⁄ 2)(2x − 2) + (3 ⁄ 4)(2x) − (−x). The first part (the part before the + sign) becomes −x + 1. The next part (from the + sign to the next − sign) becomes + (3 ⁄ 2)x. The rest becomes + x. So the whole thing is now −x + 1 + (3 ⁄ 2)x + x. We now can combine the three multiples of x. Remember that x is the same thing as 1x and −x is the same thing as −1x. Since −1 + 3 ⁄ 2 + 1 = 3 ⁄ 2, the whole thing is the same as 3 ⁄ 2x + 1. (In this case there was only one number without an x when we got to the last step. If there had been more than one, we would have added and subtracted them, just as we did with the numbers in front of the x's.)