Answer:
1) The rate of change represents the number of stamps she adds each month.
2) The rate of change is 3 stamps per month
3) How many stamps she has in her collection before she starts adding 3 every month.
4) 8 stamps.
Step-by-step explanation:
 
        
                    
             
        
        
        

an is the 'nth' term
a1 is first term
d=common difference (found by doing 

)
n=numerical representation of which term
 
        
             
        
        
        
42 because--------------------------------------------------------------................................