Answer:
(B) Hire the firefighter if the cost of the new firefighter is less than $75,000. 
Explanation:
The city should hire the Firefighter only if the cost of new firefighter is less than $75,000.
Since $5 x 15000 residents = $75, 000.
Therefore it is still beneficial to hire a new firefighter if the cost is less than $75, 000
 
        
             
        
        
        
 The answer would be False
        
                    
             
        
        
        
It gives you more ideas to make the final product better than what it original product
        
             
        
        
        
Not going to give a full solution, but with every tree they remove, they plant a new tree and they can turn to more Eco-friendly means of manufacturing, such as using non-hazardous materials. 
I hope this helps give you a start on where to begin. Just go with this and research deeper.