SOLUTION: A boat travels at a constant speed of 20 miles per hour, relative to the water, as it makes a trip downstream and then returns. If the initial trip downstream takes the boat 30 min

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A boat travels at a constant speed of 20 miles per hour, relative to the water, as it makes a trip downstream and then returns. If the initial trip downstream takes the boat 30 min      Log On


   

Question 897823: A boat travels at a constant speed of 20 miles per hour, relative to the water, as it makes a trip downstream and then returns. If the initial trip downstream takes the boat 30 minutes and the return upstream takes the boat 40 minutes, what is the speed of the current?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi

D = rt

%2820mph%2Bc%29%281%2F2%29+=+%2820mph-c%29%282%2F3%29|Multiplying thru by 6 so as all denominators = 1 

%2820mph%2Bc%293+=+%2820mph-c%294

   7c = 20

    c = 20/7 mph