Question 1206064
With a tailwind, an aircraft can fly 408 miles in 3 hours. Against 
this same wind, the aircraft can fly the same distance in 4 hours. 

Find the effect of the wind and the average airspeed of the aircraft. 
<pre>

             A = average airspeed of plane
             w = speed of wind

             | DISTANCE |   RATE  |  TIME | 
with wind    |   408    |   A+w   |   3   |     
against wind |   408    |   A-w   |   4   |

             {{{matrix(3,5,

DISTANCE,""="", RATE, ""*"", TIME,
     408,""="", (A+w) , ""*"", 3,
     408,""="", (A-w),  ""*"", 4)}}}

             {{{system(408=3A+3w,408=4A-4w)}}}
 
         Divide 1st equation by 3, 2nd equation by 4:

             {{{system(136=A+w,102=A-w)}}}

        Add the two equations:

             {{{238=2A}}}
             {{{119=A}}}

         Air speed = 119 mph

         Subtract the two equations:

             {{{34=2w}}}
             {{{17=w}}}

         Wind speed = 17 mph

Edwin</pre>