Hi guys, I was pointed to here from another forum and was wondering if you could help me with this question. I would show you my working for it...but unfortunatly i have none as i cant even begin to start on it :( I have thought that maybe it is to do with simultaneous equations but cannot see a way of implimenting that. Every time i try and solve it i end up proving what i started with in the first place (like 1=1 or something silly :uhh: ). Anyway, ive read the sticky and i appreciate that im not going to be hand-fed the answer but any pointers would be fantastic. Thanks very much for any help! And heres the question... The speed of light is now 20ms^-1, and someone gets on a bike and goes at 19.999ms^-1. The person on the bike is 60 years old and you are observing the person on the bike moving past you, you are 20 years old. What is the minimum time the person on the bike would have to continue cycling for so at the end of the journey they are younger than you?