Train X starts from A to reach B and train Y start from B to reach A. Find the ratio of the time taken by the trains to reach to their respective destination after crossing each other if the ratio of their speed is 9 ∶ 10 ?
1
10 ∶ 9
2
9 ∶ 10
3
81 ∶ 100
4
100 ∶ 81