2.77 If two people, A and B, run on a circular track at their respective constant speeds, and if they start from the same point and run in opposite directions, B takes another 8 minutes to reach the starting point after their first meeting. It is known that A takes 6 minutes to complete one lap. Therefore, how long does B take to complete one lap?
(A) 11 minutes.
(B) 12 minutes.
(C) 14 minutes.
(D) 16 minutes.
("Zu Chongzhi Cup" Junior High School Mathematics Invitational Competition, 1989)
［Solution］Let it take $x$ minutes for person B to run one lap. According to the problem, we get the proportion $(x-8): 8=6: x$, which simplifies to $x^{2}-8 x-48=0$. Solving and taking the positive root,
$$
x=12 \text {. }
$$

Therefore, the answer is $(B)$.