Question 1205974
<br>
Let x be the speed of the wind. Then the speed of the plane with the wind is 210+x, and the speed against the wind is 210-x.<br>
The times are the same, so the ratio of distances is the same as the ratio of speeds:<br>
{{{520/320=(210+x)/(210-x)}}}
{{{320(210+X)=520(210-X)}}}
{{{67200+320X=109200-520X}}}
{{{840X=42000}}}
{{{X=50}}}<br>
ANSWER: 50mph<br>
CHECK: 520/320=52/32=13/8
(210+50)/(210-50)=260/160=26/16=13/8<br>