A and B together take 9 days less to finish a work as compared to when B works alone. Also. A and B
together take 4 days less to finish a work as compared to when A Works alone. Find the ratio of the number
of days taken by A and B individually to complete the work.

let time taken by A and B, be x. Then time taken by B alone would be x+9 days, and for A alone would be x+4.
Then, time taken by A+B= Time taken by A and B individually.
1/X=1/(X+4) + 1/(X+9)

Solving for X, gives us X=6.
Time taken by A alone=X+4=6+4=10 days
Time taken by B alone= X+9= 6+9= 15 days

Required ratio is= 10/15= 2/3

2:3