Answers

2014-11-12T18:40:34+08:00
Let 'x' be the speed of Haribon
      'y' be the speed of the wind
Going with the wind you'll have the equation as
x + y = 90   ---equation 1
Flying against the wind you'll have it as:
1/2x - y = 30  ---equation 2
multiply equation 2 with 2
1/2x - y = 30
x - 2y = 60     ----equation 2'
subtract equation 2' from equation 1
    x + y = 90
-  x - 2y = 60
         3y = 30
           y = 10kph
substitute y=10 to equation 1
x + y = 90
x + 10 = 90
x = 90 - 10
x = 80 kph
Therefore the Philippine Eagle is flying at the speed of 80kph while the wind is blowing at 10kph.
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