Answer:
 25.3m
Step-by-step explanation:
Given parameters: 
Final velocity = 4.5m/s
Acceleration = 0.4m/s² 
Time taken = 12s 
Unknown: 
Distance she moved down hill = ? 
Solution: 
To solve this problem, we use the expression below: 
 v² = u² + 2aS 
v is the final velocity 
u is the initial velocity 
a is the acceleration 
S is the distance 
 4.5² = 0² + (2 x 0.4 x S)
 20.25 = 0.8S 
 S = 25.3m