SOLUTION: Please help me set up this problem: "The excursion boat Holiday travels 35 km upstream and then back again in 4 hours and 48 minutes. If the speed of the Holiday in still water

Algebra ->  Rational-functions -> SOLUTION: Please help me set up this problem: "The excursion boat Holiday travels 35 km upstream and then back again in 4 hours and 48 minutes. If the speed of the Holiday in still water       Log On


   

Question 427561: Please help me set up this problem:
"The excursion boat Holiday travels 35 km upstream and then back again in 4 hours and 48 minutes. If the speed of the Holiday in still water is 15 km/ hour, what is the speed of the current?"
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Holiday speed=15 kmph
current speed =x kmph

upstream speed =15-x
downstream speed =15+x
Total distance = 35 km Total Time=4.80 hours
Time upstream + time downstream =
35/(15- x)+35/( 15+x)=4.8
35(15+x)+35(15-x )=4.8
525+35x +525-35x=4.8(15^2-x^2)
1050=4.8(225-x^2 )
1050=1080-4.8x^2
4.8x ^2 =30
x^2=6.25
x= 2.5 km/h
CHECK
35/(15- 2.5 )+35/(15 +2.5)=
35/12.5 +35/17.5
2.8+2=4.8