Answer:
1.8 mph
Step-by-step explanation:
Speed of the steamer in still water is 18 mph.
Speed of the current = x mph.
1. The steamer going downstream traveled the distance between two ports in 3 hours. Traveling downstream the current "helps" the steamer, then the speed is 18 + x mph.
The distance traveled downstream = 3(18 + x) miles.
2. The steamer going upstream traveled the distance between two ports in 3 hours 40 minutes that is hours. Traveling upstream the current "interferes" the steamer, then the speed is 18 - x mph.
The distance traveled upstream miles.
3. The distances are the same, so
Solve this equation: