Ritu can row downstream 20 km in 2 hours, and upstream 4 km in 2 hours. Find her speed of rowing in still water and the speed of the current.

Explanation

Let the speed of the man in still water be x km/hr and let the speed of current by y km /hr .
Speed upstrem = `( x+ y ) km//hr `.
Speed upstream = ` ( x - y ) km//hr `
But, speed downstream = ` ("distance")/("time") = ( 20 )/( 2) ` km /hr = 10 km/ hr.
And, speed upstream = ` ("distance ")/("time ") = (4)/(2)` km /hr = 2 km /hr .
` therefore x+ y = 10 " " ` ... (i) and `x - y = 2 " " `... (ii)
Adding (i) and (ii), we geet ` 2x = 12 rArr x = 6 `
Putting ` x = 6 ` in (i), we get ` 6 + y = 10 rArr y = 4 `.
Thus, ` x = 6 and y = 4 `.
Hence, the speed of the man in still water is 6 km/hr and the speed of the current is 4 km/hr.