A gardener wants to create a triangular garden in the shape of a right triangle with shortest side length x – 2y ft. and the middle length side x + 4y ft. What is an algebraic expression for the area of the garden? Be sure to multiply this out and express in simplest correct mathematical form, including units.

area = (1/2)(x-2y)(x+4y)

= (x^2 + 2xy - 8y^2)/2 ft^2