A person A is trying to keep his balance while on sled B that is sliding down an icy incline . Letting mA = 78 kg and mB = 25 kg be the masses of A and B, respectively, and assuming that there is enough friction between A and B for A not to slide with respect to B, determine the value of the normal reaction force between A and B as well as the magnitude of their acceleration if θ = 20 degrees. Friction between the seld and the incline is negligible.