Atriangle is cut from a rectangle. the height of the triangle is half of the unknown side length s s . the area of the shaded region is 84 square inches. write an equation you can use to find the side length s s .

Sanderson is having trouble with his assignment. his shown work is as follows: − 3 7 7 3 = − 3 7 × 7 3 = − 21 21 = −1 however, his answer does not match the answer that his teacher gives him. complete the description of sanderson's mistake. find the correct answer.