When one end of a seesaw is 9 feet above the ground the other end of the seesaw is 21 feet above the ground so how many feet above the ground will the ends be when the seesaw is level?

To find the height of the seesaw when it is level, we need to calculate the average of the two heights. The current heights are 9 feet and 21 feet. The average height is (9 + 21) / 2 = 15 feet. Therefore, when the seesaw is level, both ends will be 15 feet above the ground.