Since we know that our area needs to be less than or equal to 750 square feet.
We can just replace area on the left side of this inequality with the other way
we know how to express it, length times width. And then, plugin those side
lengths using these quantities down here. So the new length, of Grant's booth,
will be 20 feet, the original 20 feet, plus x, the amount that he's adding on.
So we have 20 plus x and then that's multiplying it by the new width, which will
be 15 plus x. This quantity will be the new area, which we know must be less
than or equal to 750. So here's our inequality.