Traveling along a river, a man in a row boat loses his hat when he passes under a bridge, but he keeps going in the same direction. In 15 minutes, he realizes that he lost his hat, and rows his boat the other way until he is able to retrieve his hat 1 km away from the bridge. What is the speed of the river's current?

The speed of the river's current is

Step-by-step explanation:

Let's begin by explaining that Speed is a relation between an object's traveled distance  in a given time :

So, in this situation the man traveled a distance for a time before realizing he lost his hat.  

Keeping this information in mind we can calculate the speed of the river's current, since we already have a reference point: the bridge where the hat fell.

Then:

This is the speed of the river's current

-7

step-by-step explanation:

x^2 + 18x + 74 = (x + 9)^2 - 81 + 74

= (x + 9)^2 - 7.

so q = -7.