A boat can row upstream at 10 km/h and downstream at 18 km/h. If m is the speed of boat in still water and n is the speed of stream then $m+n $ is :

18 km/h

The correct answer is Option (2) → 18 km/h

m = Speed of the Boat

n = Speed of the Stream

∴ Speed of Boat, rowing downstream,

$m-n=10$   ....(1)

Speed of Boat, rowing upstream,

$m+n=18$   ....(2)

Add equation (1) and (2), we get

$2m=28$

$m=14⇒n=4$

$∴m+n=18$