Question 1192914
<pre>
                SPEED      TIME       DISTANCE

DOWNSTREAM       k+c        2          2(k+c)=30

UPSTREAM         k-c       10         10(k-c)=30
</pre>
The distances are equal.

{{{system(2(k+c)=30,10(k-c)=30)}}}


{{{system(k+c=15,k-c=3)}}}--------solve this for k and c.