SOLUTION: A motorboat heads upstream on a river that has a current of 3 miles per hour. the trip upstream takes 5 hours, and the return trip takes 2.5 hours. what is the speed of the motorbo

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Question 162164This question is from textbook
: A motorboat heads upstream on a river that has a current of 3 miles per hour. the trip upstream takes 5 hours, and the return trip takes 2.5 hours. what is the speed of the motorboat? (assume that the motorboat maintains a constant speed relative to the water) This question is from textbook

Answer by KnightOwlTutor(293) About Me  (Show Source):
You can put this solution on YOUR website!
When you are traveling upstream you are going against the current so you have to overcome the speed of the current which will slow you down.
Rate of motorboat upstream is x-3
When you are traveling downstream the current contributes to your speed
Rate of motorboat downstream x+3
Distance traveled is the same
(x-3)5=(x+3)(2.5)
5x-15=2.5x+7.5
add 15 to both sides
5x=2.5x +22.5
Subtract 2.5x from both sides
2.5x=22.5
Divide both sides by 2.5
x=9 miles per hour
Let's double check
(9-3)*5=30
12*2.5=30