Answer: im not sure
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
The equation is given by:

Step-by-step explanation:
During last years's charity walk, she raised $45.50.
During this years walk, she raised n, which is 7/10 of this amount. So, the equation is given by:

 
        
             
        
        
        
See attachment although I gather this is not your question. I did the graph(s) for the function, 
 
        
        
        
If his water to cement ratio is 20 to 30, this means that if he uses 20 liters of water, he'd use 30 liters of cement. 
The total mixture would then be 20+30=50 liters. 
and the water would be 20/50=0.4 or 40% of the total mixture.