Final answer:
The speed of the boat in still water is 30 mph and the speed of the current is 10 mph.
Step-by-step explanation:
To find the speed of the boat in still water, we can use the formula:
Speed of boat in still water = (Speed downstream + Speed upstream) / 2
Substituting the given values :-
Speed downstream = 280 miles / 7 hours
= 40 mph,
Speed upstream = 280 miles / 14 hours
= 20 mph
Speed of boat in still water = (40 mph + 20 mph) / 2
= 30 mph
To find the speed of the current, we can subtract the speed of the boat in still water from the speed downstream:
Speed of current = Speed downstream - Speed of boat in still water
= 40 mph - 30 mph
= 10 mph
Therefore, the speed of the boat in still water is 30 mph and the speed of the current is 10 mph.