This is a very good question to know about. People who make tests really like it.
The way to solve it is to make the slower car stop and use the difference in speed = to the rate. then do it as an ordinary d = r*t problem.
The difference in speeds  is 44 - 36 = 8 miles/ hour.
d = 260 miles
r = 8 mph
t = ???
t = d/r
t = 260/8
t = 32.5 hours.
Thats 32 1/2 hours.
        
             
        
        
        
The break ended at 4pm when he was at 15 km.
 The ride ended at 6pm when he was at 45 km.
 From 4 to 6pm he rode 45 - 15 = 30 km.
 
        
                    
             
        
        
        
you will have 1/4 or 25% probability to pick a black sock because 
4 blue socks + 5 gray socks + 3 black socks = 12 socks. but you need to pick one of the 3 black socks so 3 out of 12 or 3/12. simplify to 1/4