You have to write an expression to represent this situation. w can be the width, and the length can be 2w-10. To fnd the area, you multiply these together. w(2w-10) is 2w^2 -10w. From there, 15 is the only value of w that satisfies the equation, so w=15. Substitute 15 into your expression for lngth, and 2(15)-10 is 30-10 is 20, so the length is 20.
