Question 242009
a. 3000m in 50 sec is 60 m/s (3000/50); so the river is flowing at 20 m/s (80 - 60)


b. their downstream speed is 100 m/s (80 + 20); so it takes them 30 sec (3000 / 100) to travel downstream




just a comment ___ 80 m/s is about 180 miles per hour
___ perhaps the seconds in this problem should be minutes?