Please clarify: Is the second "w" in the denominator, so this is really "A = 250/pi", or is it in the numerator, so this is "A = (250/pi)w<sup>2</sup>"?
Are you working from the definition (using limits)? If not, then just apply the rules they've given you. (The rule you use, of course, will depend on which of the above is the intended function.)
If you get stuck, please reply showing what you have tried. Thank you.
Eliz.