Math Is Fun Forum

Hello everyone! I'm new here, and from what Ive seen this site will be able to help me get a passing mark for Math year!!

I've come across a problem which I'm really unsure about. and I was wondering if you guys could help me out here!

4) A group of hikers is to travel (x) km by bus at an average speed of 48 km/h to an unknown destination. They then plan to walk back along the same route at an average speed of 4.8km/h and to arrive back 24 hours after setting out in the bus. If they allow 2 h for lunch and rest, how far must the bus take them?

So, My problem is, I've completely forgotten how I might go about rewriting this situation as a set of linear equations (which is what I am almost certain I need to do!)

I've worked out that m (gradient) would be 48 (as m = rise over run, which just so happens that with my distance versus time graph (I seem to be using) km over time looks exactly the same) - So, according to me, m = 48..

I also know that x is just x, isn't it?? but how do I find out that Y intercept??? I've looked all over the place and cannot find out!!

anyways, thanks for listening, any insight to this would be greatly appreciated.