QR How you solve this?

[299678]

Q. a boat takes 4 hours to travel a particular distance upstream and 3 hours downstream. IF the speed of the boat in still water is 4 mph, what is the speed of the river?

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[Streetwolf]

Q. a boat takes 4 hours to travel a particular distance upstream and 3 hours downstream. IF the speed of the boat in still water is 4 mph, what is the speed of the river?

Rate * time = distance

Time(up) = 4 hr
Time(down) = 3 hr
Rate(up) = (4 - r)mph where r = river's speed (WHY MINUS?)
Rate(down) = (4 + r)mph (WHY PLUS?)

Distance is the SAME (WHY?)

If the distance is the same, then rate(up) * time(up) = rate(down) * time(down).

Can you solve this from here?
What are you solving for?