Hanged Lamp in an Elevator

A lamp hangs vertically from a cord in a descending elevator. The
elevator has a deceleration of 2.4m/s^{2} before coming to a stop.

a) If the tension in the cord is 89N, what is the mass of the lamp?

b) What is the tension in the cord when the elevator ascends with
an upward acceleration of 2.4m/s^{2} ?