Hi boomgoesthegmat,

I'm going to give you a couple of hints so that you can solve this question on your own:

We're asked to figure out the area of the PATIO. The patio is essentially a rectangle with a 'corner' removed from it. The width of that rectangle is 40ft and the height is 35ft, so if we had a FULL rectangle, it would have an area of (40)(35) = 1400 ft.

However, that 'corner piece' is removed, so we have to figure out its dimensions, then subtract that area from 1400 to get the area of the patio.

So, how to figure out the dimensions of that corner....
Notice how the 'left side' is 15ft and the right side is 35ft. What does that mean about the height of the corner piece?
Notice how the 'top side' is 40ft and the bottom side is 20ft. What does that mean about the width of the corner piece?

You should be able to calculate the dimensions and the area and finish the question from here.

GMAT assassins aren't born, they're made,
Rich