Question 976086
In a day (24 hours) Nick paints 4 fences. 
In a day James and Nick paint 6 fences. 

Nick still paints 4 fences in a day, so James painted 2. James takes 12 hours per fence. 



The above is a fool proof method to solve this problem, but it lacks the algebra type of set up the teacher might like. 

Nick's rate is 1/6 fence per hour. This is key, as hours per fence will not work.  

Nick + James' combined rate is 1/4 fence per hour.

1/6 + X = 1/4

4/24 + X = 6/24

X = 2/24, i.e. James' rate is 1 fence per 12 hours.