`t_(P)=d/sqrt(V_(B)^(2)-V_(w)^(2))=d/sqrt(5^(2)-3^(2))=d/4`
`t_(Q)=d/V_(B)=d/5,t_(P)=t_(Q)+Deltat`
`d/4=d/5+x/V_(man),But x=V_(w)d/V_(B)`
`d/4=d/5+(V_(W)d)/(V_(B)V_(man)),d/4=d/5+(3d)/((5)V_(man))`
`1/4-1/5+(3)/(5V_(man)), 1/20=3/(5V_(man))`
`V_(man)=((3)(20))/5=12kmph`
![image](https://learnqa.s3.ap-south-1.amazonaws.com/images/16117900602728943461611790060.png)