Answer: C.  6
Step-by-step explanation:
Given : Time taken by Machine R to do the job = 36 hours 
Time taken by Machine S to do the job = 18 hours
Let x be the number of each type of machine to do the job.
Then , according to the question the required equation will be :-

Hence, the number of machines of type R were used =6
 
        
             
        
        
        
2/3 is the answer in lowest terms. i hope this helps!
        
                    
             
        
        
        
Answer:
B. 1
Step-by-step explanation:

 
        
             
        
        
        
Plug in 20 to W making 20-8, so your answer would be 12 :)