Linear equations are an equation between two variables that makes a straight line on a graph. You need to find the value of x or y. You can usually substitute numbers in for x or y until you get what they're equaling.
A) x=1/2
You can get this by first finding the like terms. In this case it would look like 4x-2=0. Then you'd move the constant to the right to get 4x=2. Then just divide both sides by 4 to get 1/2.
Hope this helped! :)