SOLUTION: If a boat goes downstream 72 miles in 3 hours and upstream 60 miles in 6 hours, the rate of the river and the rate of the boat in still water respectively are _______

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Question 126539: If a boat goes downstream 72 miles in 3 hours and upstream 60 miles in 6 hours, the rate of the river and the rate of the boat in still water respectively are ________?
Answer by marcsam823(57) (Show Source):
You can put this solution on YOUR website!
The basic formula to remember here is or
distance/time = rate
1. First we need a rate of speed for travel both downstream and upstream.
a. Downstream:
The boat travelled 72 miles in 3 hours or miles per hour.
b. Upstream:
The boat travelled 60 miles in 6 hours or miles per hour.
2. Now that we have these rates we can establish some variables
Let x = the rate of the boat in still water
Let y = the rate of the river
Let x + y = 24 (downstream rate of boat)
Let x - y = 10 (upstream rate of boat)
3. Add the 2 equations:

+

3. Substite and solve for y:

4. Check using the other equation:

This is true so our answers are correct.
The boat's speed in still water is 17 mph.
The rate of the river is 7 mph.

SOLUTION: If a boat goes downstream 72 miles in 3 hours and upstream 60 miles in 6 hours, the rate of the river and the rate of the boat in still water respectively are ________?