A boy standing by the side of a railway track finds that an Up train crosses him in 8 seconds and a Down train of twice the length of that of the Up train crosses him in 20 seconds. How long (in seconds) will the two trains take to cross each other?
1
20 sec
2
15 sec
3
\(12\frac{1}{3}\) sec
4
\(13\frac{1}{3}\) sec