Damon answered a very similar question a couple of days back
http://www.jiskha.com/display.cgi?id=1327699984
tom has a collection of 50 cds and nita has a collection of 38 cds. Each month tom adds two cds and nita adds four how many months will it take until they have the same amount?
3 answers
In 6 months
It is 3 months . I don't really remember how to show my work but I remember it was 3 months .