A75.0 kg person stands on a scale in an elevator.
(a) what does the scale read (in n and in kg)when the elevator is at rest?

The person's weight is  (mass) x (gravity) = (75 kg) x (9.8 m/s²) = 735 newtons.

When the elevator is at rest, or moving up or down at a constant speed,
the scale reads 735 newtons.

When the elevator starts moving upward from rest, or moving down
but getting slower, the scale reads a higher number of newtons.

When the elevator starts moving downward from rest, or moving up
but getting slower, the scale reads a smaller number of newtons.

A properly marked scale will never read anything in kilograms,
because 'kilogram' is a unit of mass, not force or weight.