Question 1199975
<pre>
                      SPEED             TIME           DISTANCE
WITHWIND               7+w              54/(7+w)        54
AGAINSTWD              7-w              30/(7-w)        30
</pre>
The time is the same amount for both directions.
{{{54/(w+7)=30/(-w+7)}}}

-

{{{9/(w+7)=5/(-w+7)}}}

{{{9(-w+7)=5(w+7)}}}

{{{-9w+9*7=5w+5*7}}}

{{{28=14w}}}

{{{highlight(w=2)}}}