Question 201088
Let {{{w}}} = wind speed
Let {{{s}}} = speed of plane in calm air
Let {{{t}}} = time for both trips
given:
{{{s = 180}}}
With the wind:
{{{7 = (180 + w)*t}}}
{{{5 = (180 - w)*t}}}
--------------------
{{{7 = 180t + wt}}}
{{{5 = 180t - wt}}}
Add the equations
{{{12 = 360t}}}
{{{t = 1/30}}} hrs
and, since
{{{5 = (180 - w)*t}}}
{{{5 = (180 - w)*(1/30)}}}
{{{150 = 180 - w}}}
{{{w = 180 - 150}}}
{{{w = 30}}}
The windspeed is 30 mi/hr