SOLUTION: Airplane A travels 2800 km at a certain speed.Plane B travels 2000 km at a speed 50 km/h faster than plane A in 3 hrs less time. find the speed of each plane?

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Question 1061144: Airplane A travels 2800 km at a certain speed.Plane B travels 2000 km at a speed 50 km/h faster than plane A in 3 hrs less time. find the speed of each plane?
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Constant Travel Rate Rule, RT=D 

                SPEED      TIME       DISTANCE
A               r          t           2800
B               r+50       t-3         2000

system%28rt=2800%2C%28r%2B50%29%28t-3%29=2000%29

Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
.
Airplane A travels 2800 km at a certain speed.Plane B travels 2000 km at a speed 50 km/h faster than plane A in 3 hrs less time.
find the speed of each plane?
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Let "u" be the speed of the faster plane (plane B).
Then the speed of the plane A is (u-50) km/h.

The literal translation of the condition is this equation:

2800%2F%28u-50%29+-+2800%2Fu = 3.

Indeed, 2800%2F%28u-50%29 is the time for the plane A, while 2800%2Fu is the time for plane B.

To solve the equation, multiply both sides by u*(u-50). You will get

2800u - 2800(u-50) = 3u*(u-50),  or

3u^2 - 150u - 140000 = 0.

Solve this quadratic equation using the quadratic formula.