সব প্রশ্নে ফিরে যান
Math
If a boat goes 7 km upstream in 42 minutes and the speed of the speed of the stream is 3 kmph, the speed of the boat in still water is
A) 4.2 km/hr
B) 9 km/hr
C) 13 km/hr
সঠিক উত্তর
D) 21 km /hr