Question 974123
A plane can travel 470mph with the wind and 390mph against the wind. What is the speed of the plane if the air is still?
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let x=speed of plane in still air
let c=speed of wind
x+c=speed of plane downwind
x-c=speed of plane against the wind
..
x+c=470
x-c=390
add
2x=860
x=430
What is the speed of the plane if the air is still? 430 mph