A boat travels about 6 kilometers per hour in still water. If the boat is on a river that flows at a constant speed of
kilometers per hour, it can travel at a speed of (6+r) kilometers per hour downstream. On one particular river, a
boat travels 12 kilometers down stream. The amount of time it takes the boat travel depends on the speed of river
and is expressed by the equation t(r) =
12
(6+r)
The graph is shown below.
What does t(3) mean in this situation?
At what value of r does the graph have a vertical asymptote? Explain
how you know and what this asymptote means in this situation.