A 75.0 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.