hey can sumone help me with this question...becasue i forgot how to do them..and its due tomorrow for school..any help will be great!! thanks in advance

Water from two hoses can fill a swimming pool in 4 hours. If each hose is used separately it takes 6 hours longer to fill the pool with the smaller hose than the larger hose. How long would it take to fill the pool if only the smaller hose is used.

thanx

PLEASE HELP