Two cyclists M and N starts from A, B and travels forward to B and A respectively. Once they reach to B and A, they turn back and travel to their starting points. If they meet 36 km from A for the first time and 18 km from B for the second time, then find the ratio of speeds of M and N.
(A) 2:3
(B) 3:2
(C) 4:5
(D) 5:4