The weight of Tom is the force, that he exerts on the elevator's floor, the Normal force. The total force on Tom in the vertical direction is the vector sum of the normal force and gravity. The total force gives the total acceleration, which is known to be 0.55. The Normal force is then given by:
N = m(a + g)
N normal force
a = 0.55
g = 9.81
m = 75