Answer:
Speed of the current of the river = 3 mph
Step-by-step explanation:
Let the speed of the current of the river he is in be u mph.
He rafts 16 miles with the river current. At the end of 16 miles, he turns around and rafts the same distance against the river current. The journey takes him 4 hours overall.He can raft at a speed of 9 mph in still water
That is
[tex]\frac{16}{9+u}+\frac{16}{9-u}=4\\\\\frac{4}{9+u}+\frac{4}{9-u}=1\\\\36+4u+36-4u=81-u^2\\\\u^2=81-72=9\\\\u=3mph[/tex]
Speed of the current of the river = 3 mph
