Question 1185907
Upstream
{{{10/(20-6)}}}
{{{10/14}}}
{{{5/7}}}{{{hours}}}


Downstream
{{{10/(20+6)}}}
{{{10/26}}}
{{{5/13}}}{{{hours}}}


Average speed of whole round-trip:
{{{(10+10)/(5/7+5/13)}}} {{{kilometers}}}

Simplify and compute.




-----------------------------------------
-----------------------------------------


<pre>
              SPEEDS         TIMES               DISTANCES

upstream        20-6         10/(20-6)                10

downstream      20+6         10/(20+6)                10

TOTALS                     10/(20-6)+10/(20+6)       2*10
</pre>
Average Speed, round-trip

{{{(2*10)/(10/(20-6)+10/(20+6))}}}


{{{(10/10)(2/(1/(20-6)+1/(20+6)))}}}


{{{highlight_green(2/(1/(20-6)+1/(20+6)))}}}---------------compute the value.