<PRE><B>Question 280230</B>
boat will go 15 mph in still water,he can go 12 miles down stream in the same time as it takes him to go 9 miles upstream,,then what is the speed of the current
----------------------------------
Downstream DATA:
distance = 12 miles ; rate = 15+c mph ; time = 12/(15+c) hrs
--------------------------------------
Upstream DATA:
distance = 9 miles ; rate = 15-c mph ; time = 9/(15-c) hrs
--------------------------------------
Equation:
time = time
12/(15+c) = 9/(15-c)
12*15-12c = 9*15+9c
21c = 3*15
current = 2.14 mph 
========================
Cheers,
Stan H.</PRE>