A school wishes to enclose its rectangular playground using 280 meters of fencing. Suppose that a side length (in meters) of the playground is $x$, as shown below.

Step 1 ：Let's denote the length of the playground as x and the width as y. The perimeter of the rectangle is given by the formula 2*(length + width), which in this case is 2*(x + y).

Step 2 ：We know that the total length of the fencing is 280 meters, so we can set up the equation 2*(x + y) = 280 to solve for the possible values of x and y.

Step 3 ：The solution to the equation is y = 140 - x. This means that for any given length x, the width y of the playground would be 140 - x meters.

Step 4 ：This makes sense because the total length of the fencing is fixed at 280 meters, so if we increase the length of the playground, we would have to decrease its width to keep the total length of the fencing constant.

Step 5 ：Final Answer: The width of the playground in terms of x is \(\boxed{y = 140 - x}\).