Question 1059114
<pre>
                 SPEED       TIME      DISTANCE
UPSTREAM          r-5         t           7
DOWNSTREAM        r+5         t          20
</pre>


The problem form is so common, I will generalize.
<pre>
                 SPEED       TIME      DISTANCE
UPSTREAM          r-c         t           p
DOWNSTREAM        r+c         t           d

p is for distance uPstream and d is distance Downstream.

The unknown variables are r and t.  
</pre>

You can form an equation because t is the same number for both directions and according to the constant travel rates rule.


{{{highlight(p/(r-c)=d/(r+c))}}}
Solve for r.