Question

A boat goes 24Km upstream and 28Km downstream in 6hrs.it goes 30Km
up stream and 21Km downstream in 6 1/2 hours.Find the speed of the boat in still water and also speed of stream.

Answer 1

if speed of the boat be x and stream speed be y 

from the given question, 

24/(x-y) + 28/(x+y) = 6 
30/(x-y) + 21/(x+y) = 6.5 

Taking 1/(x-y) as X and 1/(x+y) as Y 
24X + 28Y = 6 
30X + 21Y = 6.5 

solving for X and Y==> 
X = 1/6 and Y = 1/14 

so x-y = 6 and x+y = 14 
hence 
x = 10 kmph and y = 4kmph

Answer 2

this is the answer to your question hope it helps