It might be helpful if you translate the paragraph of info into maths.
So in this case, let's say everything with subscript 1 refers to the journey PQ, while subscript 2 refers to the journey QR.
What is u_1? v_1? s_1? u_2? etc.. You might end up having a lot of blanks (for instance, u_1 is unknown here), but it gives you clues as to what the missing pieces are before maybe formulating a plan of attack.
Please show your work/thoughts, per discussion board rules.
P.S. If I'm counting correctly, you should have 10 quantities that you (a) have information about; or (b) not know, but will be the same as some other quantity; or (c) not know, and you really want to find; or (d) not know, but irrelevant.
Which quantity falls in which category? Well, depends on how much you've worked on, really. That's problem-solving! Also 10 isn't really that many.
P.P.S. Usually a nice diagram helps consolidate info. It works for me and many, many, many people, at least.