How would I solve this?

[velvet pendant]

1. Ask your question and show the work you've done so far. If you've posted a screenshot of a question, specify which part you need help with.
2. Wait patiently for a helper to come along.
3. Once someone helps you, say thank you and close the thread with:

   +close
   

4. Feel free to nominate the person for helper of the week in #helper-nominations
5. Do not ping the mods, unless someone is breaking the rules.
6. If you're happy with the help you got here, and the server overall, you can contribute financially as well:

[sonic shoal]

B lies on the line 3x + 2y = 12, hence 3p + 2q = 12
|OB| = 10, hence by Pythagoras's theorem p^2 + q^2 = 100

[rough flame]

sry to ping but does O mean origin