Math
posted by Sarah .
JJ's boat will go 15 mph in still water. If he can go 12 mph downstream in the same amount of time it takes to go 9 mph upstream, what is the speed of the current?

Math 
Henry
Vb + Vc = 12.
Vb  Vc = 9.
Add the Eqs:
2Vb = 21.
Vb = 10.5 MPH.
Vc = 1.5 mph.
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