Question

A boat travels upstream from Point A to Point B in 7 hours. The return trip takes only 3.5 hours because the boat travels 3 miles per hour faster downstream due to the current. How far does the boat travel upstream?

Answer 1

because the boat travels the distance twice as fast when going 3 three miles/hour faster the original speed must be 3 miles/hour. so the distance upstream would be 21 miles/hour.