Answer: 0.455 m/s^2
Step-by-step explanation:
f = ma = m x 9.8=689 (the mass is constant)
m = 78.3
now on the elevator
f = 721 = m x a
a= 10.26
the elevator is moving down because there is a increase in weight. the acceleration of elevator = 10.26-9.8 = 0.455