Faraz R. answered • 03/29/16

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Lets say the rate of the plane is x then the rate of the car is x-80.

We know their times are equal so you will solve for time for each.

The time for the plane is

d/r=t

The distance the plane traveled is 260 miles. The distance the car traveled is 100.

The time for both are equal so the distance/rate of the plane = distance/rate of the car

We said the rate for the plane was x and the rate of the car was x-80. Now we just plug in

d/r(plane) = d/r (car) Ignore the parentheses except to differentiate what they are.

260/x = 100/(x-80)

you will cross multiply to get

260x - 20800= 100x

Subtract 260x to take it to the other side and you will get

-20800=-160x

x = 130 The speed of the plane.