Answer:
- boat: 44 mph
- current: 8 mph
Explanation:
The average speed upstream is ...
speed = distance/time
upstream speed = (180 mi)/(5 h) = 36 mi/h
The average speed downstream is ...
downstream speed = (260 mi)/(5 h) = 52 mi/h
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The upstream speed is the difference between the speed of the boat (b) and that of the current (c):
36 = b - c
Likewise, the downstream speed is the sum of those of boat and current:
52 = b +c
Adding these equations gives ...
88 = 2b
44 = b
Then the speed of the current is ...
c = b -36 = 44 -36 = 8
The boat's speed in still water is 44 mi/h; the current's speed is 8 mi/h.