Question 359035
Junior’s boat will go 15 miles per
hour in still water. If he can go 12 miles downstream in the
same amount of time as it takes to go 9 miles upstream,
then what is the speed of the current?

...
current speed =xmph
downstream speed = x+15
upstream speed = 15-x
..
downstream distance = 12 miles
time downstream = 12/x+15
..
upstream distance = 9 miles
upstream time = 9/15-x
..
these times are same
12/(x+15)=9/(15-x)
12(15-x)=9(x+15)
180-12x=9x+135
-12x-9x=135-180
-21x=-45
/-21
x=45/21
x= 2.14 mph speed of current

m.ananth@hotmail.ca