Question

a Boat goes 24 km upstream and 28 km downstream in 6 hours it goes 30 km upstream and 21 km downstream in 6 and half hours find the speed of boat in still water and also the speed of stream

Answer 1

Assuming, Speed of boat=v
Speed of stream=x

$\frac{24}{v - x} + \frac{28}{v} = 6 \: \: \: \: \: \: \: \: eqn1$
$\frac{30}{v - x} + \frac{21}{v} =6 \frac{1}{2} \: \: \: \: \: \: eqn2$
On solving both the equations we get,
$x = \frac{4}{7} v$
On putting the value of x in either eqn1 or eqn 2 we get,
$v = 14 \: kmph \: \\ x = 8 \: kmph$