UPSC 2015 CDS I Math Paper

Let the speed of the boat in still water be x km/hr and the speed ofthe current be y km/hr
Speed of the boat downstream × Time for downstream journey = Distance covered by the boat downstream
∴(x+y)×6=32
⇒6x+6y=32.........(1)
Speed of the boat upstream × Time for upstream journey = Distance covered by the boat downstream
∴(x−y)×6=14
⇒6x−6y=14.......(2)
Subtracting eq. (2) from (1), we get
12y=32−14=18
⇒y=1.5km/hr