Algebra
posted by MARIAH on .
Mattie Evans drove 250 miles in the same amount of time that it took a turbopropeller plane to travel 1250 miles. The speed of the plane was 200 mph faster than the speed of the car. Find the speed of the plane

its 450 mph

Speed = distance/time
time = distance/speed
Let x = plane speed and y = driving speed
y = x + 200
250/x = 1250/y
Substitute x + 200 for y in second equation and solve for x. Insert that value into the first equation and solve for y. Check by inserting both values into the second equation. 
Car speed = Xmi/h,
Plane speed = (X + 200) mi/h,
Eq1: d1 = X*t = 250 mi,
t = 250 / X,
Eq2: d2 = (X + 200)t = 1250 mi.
Substitute 250 / X for t in Eq2:
(X + 200)250/X = 1250,
250 + 50000/X = 1250,
50000 / X = 1250  250,
50000 / X = 1000,
Cross multiply:
1000X = 50000,
X = 50000 / 1000 = 50 mi/h = car speed.
(X + 200) = 250 mi/h = plane speed.