Answer:75 N
Step-by-step explanation:
Given
Bob is pushing the box with a force of 75 N with constant speed. Constant speed indicates that net force on the block is zero i.e. friction force is balancing the applied force.
so friction force f=75 N
If Alice is pushing an identical box with constant speed so net force acting on box must be equal to an applied force.
As the friction force is 75 N so Alice must be applying a force of 75 N