Struggling with this problem:

Question

A student stands on a bathroom scale in an elevator at rest on the 64th floor of a building. The scale reads 848 N. As the elevator starts to move up, the scale reading increases to 968 N, then changes back to 848 N. What was the acceleration of the elevator?

Answer 1

add acceleration a to the g of gravity.
mg = 9.81m = 848, so m = 86.44 kg
86.44(g+a) = 968
a = 968/86.44 - 9.81 = 1.388 m/s^2

or, m(g+a)/mg = 968/848
a = 1.388

Answer 2

848 = m g
so m = 848/g

968 = m g + m a
m a = 968 - m g = 968 - 848 = 120
a = 120/m = (120 / 848 ) g
now just put in whatever g is on your planet