Question 1012409
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R=rate of plane; W=rate of wind
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Against wind:(5 hours)(R-W)=4200km
R-W=840
R=W+840
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With wind: (4 hours)(R+W)=4200km
R+W=1050
(W+840)+W=1050
2W=210
W=105
ANSWER 1: Rate of wind = 105 km/hr.
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R=W+840
R=105+840
R=945
ANSWER 2: Rate of plane in still air = 945 km/hr.
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CHECK:
(5 hours)(R-W)=4200
(5hrs)(945-105)=4200
(5hrs)(840)=4200
4200=4200
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(4 hrs)(R+W)=4200
(4 hrs)(945+105)=4200
(4 hrs)(1050)=4200
4200=4200
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