A spring scale A and a lever scale B having equal lever arms are fastened to the roof on a...

A spring scale A and a lever scale B having equal lever arms are fastened to the roof on an elevator, and identical packages are attached to the scales as shown. Knowing that when the elevator moves downward with an acceleration of 2 ft/s2 the spring scale indicates a load of 7 lb, determine (a) the weight of the packages, (b) the load indicated by the spring scale and the mass needed to balance the lever scale when the elevator moves upward with an acceleration of 2 ft/s2.