20. There are 3 point A, B and C in a straight line such that point B is equidistant from points A and C. A boat can travel from point A to C downstream in 12 hours and from B to A upstream in 8 hours. Find the ratio of boat in still water to speed of stream. (a) 9:2 (b) 8:3 (c) 7:1 (d) 4:1 (e) 7:3​