Answer:
0.3
Step-by-step explanation:
 
        
                    
             
        
        
        
 the is just THIS ONE JIAN JUAN IS B
 
        
             
        
        
        
30 is the greatest common factor I think
        
                    
             
        
        
        
Answer:
 He will finish the rest of the problems in 32.4 minutes.
Step-by-step explanation:
Since we are given that Yan has completed 3/5 of 45 problems i.e.


Thus he has completed 27 problems 
Remaining no. of problems are 45-27 = 18
Since he complete each problem in minutes = 
So, he completes 18 problems in minutes = 18 *1.8 = 32.4 minutes
Hence , He will finish the rest of the problems in 32.4 minutes.