I don't really know if this belongs here, but I couldn't find anwhere to put it. All help appreciated.

Given that vector a = i - 2j and vector b = -3i + j find:

a) p, if 'a + xb' is parallel to -i - 3j

b) q, if 'qa + b' is parallel to 2i + j

Answers: a) 1/2

b) 1

I am looking for some help and working. Advanced thanks.