A person is standing on a weighing machine placed

A person is standing on a weighing machine placed on the floor of an elevator. The elevator starts going up with some acceleration, moves with uniform velocity for a while and finally decelerates to stop. The maximum and the minimum weights recorded are $72 \mathrm{~kg}$ and $60 \mathrm{~kg}$. Assuming that the magnitudes of the acceleration and the deceleration are the same, find (a) the true weight of the person and $(b)$ the magnitude of the acceleration. Take $g=9.9 \mathrm{~m} / \mathrm{s}^{2}$.