Question 626943
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Hi,
An airplane flight took 2 hrs. to travel 780 miles with the headwind 
and the return trip with the tailwind only takes 1.5 hrs. 
Let p and w  represent the speed of the plane in still air and the speed of the wind respectively
Question states*** Note: D = rt or  t = D/r
 2 = 780/(p-w)  &#8658; (p-w) = 780/2 = 390  &#8658; p = {{{w + 390}}}
 1.5 = 780/(p+w)    
p+w = 780/1.5= 520   
{{{w + 390}}} + w = 520
       2w = 130  
        w = 65mph   and p = 455mph    || p = {{{w + 390}}}
and****Checking our Answer
 {{{2hr = 780mi/390mph}}}
{{{1.5hr = 780mi/520mph}}}