Answer:
The answer to your question is: a = 2 m/s²
Explanation:
I' ll solve it in this way, tell me if I'm right. Because we need to consider that in the moon there is no gravity.
Data
F = 50 N
a = 4.0 m/s²
Moon
F = 25 N
a = ?
Formula
        F = m x a
First, calculate the mass
       m = F / a
       m = 50 / 4
       m = 12.5 kg
Now, calculate the acceleration
       a = F / m
       a = 25 / 12.5
      a = 2 m/s²