Question

ritu can rawa downstream 20 km 2 hour and uprtream 4k in 2 hour​

Answer 1

Step-by-step explanation:

Solution :-

Ritu speed still of water = xkm/h

speed of streame = y km/h

Upstreame = (x-y) km/h

Downstreame=(x+y)km/h

Now

Upstreame:-

$\: \: \: 2(x - y) = 4 \\ = > x - y = \frac{4}{2} \\ = > x - y = 2 \\ = > x = 2 + y \\ now \\ \: \: \: \: \: down \: streme \\ \: \: \:2( x + y ) = 20 \\ = > x + y = \frac{20}{2} \\ = > x + y = 10 \\ now \: subsitute \: value \: of\: x \: in \: x + y = 20 \\ \: \: \: \: x + y = 10 \\ = > (2 + y) + y = 10 \\ = > 2 + y + y = 20 \\ = > 2 + 2y = 10 \\ = > 2y = 10 - 2 \\ = > 2y = 8 \\ = > y = \frac{8}{2} \\ = > y = 4 \\ now \\ \: \: \: \: subsitute \: the \: value \: of \: y\: in \: x - y = 2 \\ \: \: \: x - y = 2 \\ = > x - 4 = 2 \\ = > x = 4 + 2 \\ = > x = 6$

Now

Ritu Speed still of water=x=6 km/h

Ritu speed of streame=y=4 km/h