Answer:
1.25 is the rate of growth of hairs per month.
Step-by-step explanation:
Given : L represents the length of hair.
m represents months after she shaved her head .
Equation : 
To Find: What does 1.25 mean in this situation?
Solution:
Equation : 
Since it is linear function . So, 1.25 is the slope
Slope is the rate of change per unit.
So, 1.25 is the rate of growth of hairs per month.