Question 935610
Distance = Rate * Time
.
.
With the wind,
{{{280=(R+W)*30}}}
1.{{{R+W=28/3}}}
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.
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Against the wind,
{{{280=(R-W)*40}}}
2.{{{R-W=7}}}
Add the equations together,
{{{R+W+R-W=28/3+7}}}
{{{2R=28/3+21/3}}}
{{{2R=49/3}}}
{{{R=49/6}}} {{{km/min}}}
Then,
{{{49/6-W=7}}}
{{{W=49/6-42/6}}}
{{{W=7/6}}} {{{km/min}}}