How can you find x in this equation? and if you can please answer this problem--and explain why.
Two hikers left at 9:00. The other hiked south with a speed of 4km/h while the other hiked north at 3km/h.How long can they stay connected if their walkie-talkies've got a max. range of 10km? (Sorry for the bad english, the problem was written in french).