Answer:
a) 67.8m
b) 36.8m
(both answers rounded off to 3 s.f.)
Explanation:
Please see the attached pictures for full solution.
*Instead of rewriting PF to QF +43 in part (a), you could also leave PF as it is and rewrite QF as PF -43 after the line I labelled as equation 2. The working would be about the same, just that you would not need to add 43 again in picture 3 because we would be working with PF. (PF would be factorised out instead)