a weather balloon is seen directly above a point on the ground which is 350 feet from a observer, as shown at the right. If the balloon is 840 feet high, write and solve the equation for the distance from the balloon to the base of the observer

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.