17. A passenger jet can fly 804 miles in 2 hours with a tailwind but only 776 miles in 2 hours into a headwind. Find the speed of the jet in still air and the speed of the wind.
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Jet speed = 395

Wind = 7

Explanation:

Let :

Speed of jet = x

Speed of wind = y

Distance = speed * time

With tailwind :

804 = (jet speed + wind speed) * time

804 = (x + y) * 2

804/2 = (x + y) * 2/2

x + y = 402 - - - (1)

Into a headwind :

776 = (jet speed - wind speed) * time

776 = (x - y) * 2

776/2 = (x - y) * 2/2

x - y = 388 - - - (2)

From (1)

x = 402 - y

Put x = 402 - y in (2)

402 - y - y = 388

402 - 2y = 388

-2y = 388 - 402

-2y = - 14

y = 7

x = 402 - y

x = 402 - 7

x = 395