Answer:
Speed of boat in still water = 15 km/hr
Step-by-step explanation:
Let the speed of the boat in still water = x km/hr
Speed of the stream = 3km/hr
Then effective speed of the boat when travelling upstream = x-3 km/hr
Effective speed of the boat when travelling downstream = x+3 km/hr
Time taken for traveling 36 km downstream = Time taken for traveling 24 km upstream
=> [tex]\[\frac{36}{x+3}=\frac{24}{x-3}\][/tex]
=> [tex]\[36*(x-3)=24*(x+3)\] [/tex]
=> [tex]\[36x - 108 = 24x +72\][/tex]
=> [tex]\[36x - 24x = 108 + 72\][/tex]
=> [tex]\[12x = 180\][/tex]
=> x=15
