2.45 m/s^2
Elevator is moving down.
The woman's weight is a function of the local gravity plus the local acceleration, an expression for this would be
G + A = 0.75
G = Normal attraction due to gravity
A = Weight due to acceleration.
Substituting 1 for G gives
1 + A = 0.75
Solving for A
1 + A = 0.75
A = -0.25
So the acceleration experienced is -0.25 times the acceleration due to gravity. So multiply by 9.8 m/s^2
-0.25 * 9.8 m/s^2 = -2.45 m/s^2
So the woman briefly experienced an acceleration of 2.45 m/s^2 as the elevator started moving. And since her weight decreased, that means that the elevator started moving down.
