Mechanics help

I'm not sure where to start because I don't really understand this question, and I took a look at the mark scheme but it didn't help my confusion as it was vague:
A motorcyclist is traveling along a straight road with constant acceleration, a m/s2
The motorcyclist passes point A with speed U km/h.
After 8 seconds it passes point B, where AB = 50 m. After a further 12 seconds it
passes point C, where BC = 250 m.
8 (a) Find the value of a giving your answer as an exact fraction.
8 (b) Find U.
What do I need to do?

Look at the information in chunks
"The motorcyclist passes point A with speed U km/h.After 8 seconds it passes point B, where AB = 50 m."
Construct an equation u = U, S = 50, T = 8, a = a
"After a further 12 seconds it passes point C, where BC = 250 m."
Construct an equation for the whole journey
u = U, s = , T = , a =a
Now solve 🙂 Post your two equations

Ohhh,
50 = 8u + 32a
300 = 20u + 200a
And then I can solve the simultaneous equations.
I understand now thank you very much!! I was overcomplicating it in my head.