SOLUTION: Please help me solve this word problem. A rowing crew practices at a steady rate of 9 miles per hour. When they practice in steadily flowing river, a 10-mile trip downstream takes

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Please help me solve this word problem. A rowing crew practices at a steady rate of 9 miles per hour. When they practice in steadily flowing river, a 10-mile trip downstream takes      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 972136: Please help me solve this word problem.
A rowing crew practices at a steady rate of 9 miles per hour. When they practice in steadily flowing river, a 10-mile trip downstream takes the same time as a 5-mile trip upstream. What is the rate of the river current?
I have tried 9/10 = 0.9
I have tried dividing 9/5 = 1.8
I have tried (10+5)/9 = 1.7
I have tried (9*10)/5 = 18
I have tried 9=10/x ~ 9/10 =.9 ~ .9*5 = 4.5
I do not know how to figure out the answer. It would be helpful if i could have a formula for solving the problem.
Found 2 solutions by Boreal, iloveblacky123:
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
speed= rowing speed + current or - current
r=rowing speed, c=current
distance = speed * time
10=9t +ct, where t=time t= 10/(9+c)
5=9t-ct, because it is the same time t=5/(9-c)
[10/(9+c)]=[5/(9-c)]
cross-multiply
90-10c=45 +5c
45=15c
3=c
speed downstream is 12 mph, and it takes (10/12) hours to cover 10 miles
speed upstream is 6 mph, and it takes (5/6) hours to cover 5 miles. Those fractions are equivalent.

Answer by iloveblacky123(1) About Me  (Show Source):
You can put this solution on YOUR website!
C = rate of current
so basically you are cross multiplying 10%2F%289%2Bc%29+=+5%2F%289-c%29
cross multiply 10%2A%289-c%29
which equals 90-10c
cross multiply %289%2Bc%29%2A5
which equals 45%2B5c
90-10c+=+45%2B5c
90-45+=+45
10c%2B5c+=+15c
45+=+15c
45%2F15+=+c
3=c
the answer for rate of current is 3