SOLUTION: A newer model jet plan can travel 200 mph faster than a an older model. The newer model can travel 1200 miles in the same time that the older model can travel 900 miles. What is

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Question 601553: A newer model jet plan can travel 200 mph faster than a an older model. The newer model can travel 1200 miles in the same time that the older model can travel 900 miles. What is the rate of the older model jet plane?
Found 2 solutions by josmiceli, Rcmathtutor:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = the speed of the older model
Let +t+ = time in hours older model takes to travel 900 mi
and newer model takes to travel 1200 mi
-----------------
Equation for older model:
(1) +900+=+s%2At+
Equation for newer model:
(2) +1200+=+%28+s+%2B+200+%29%2At+
-----------------------
Substitute (1) into (2)
(2) +1200+=+s%2At+%2B+200t+
(2) +1200+=+900+%2B+200t+
(2) +200t+=+300+
(2) +t+=+1.5+
and, since
(1) +900+=+s%2A1.5+
(1) +s+=+900%2F1.5+
(1) +s+=+600+
The speed of the older model is 600 mi/hr
check:
(2) +1200+=+%28+s+%2B+200+%29%2At+
(2) +1200+=+%28+600+%2B+200+%29%2At+
(2) +t+=+1200%2F800+
(2) +t+=+1.5+
OK

Answer by Rcmathtutor(12) About Me  (Show Source):
You can put this solution on YOUR website!
t=d%2Fr
Let rate of older plane = x and rate of newer plane = y
t=900%2Fx
t=1200%2Fy
Since both planes travel the given distance in the same time; their times are equal, then:
900%2Fx=1200%2Fy
900y=1200x
The newer plane travels 200 mph faster than the older (given):
y=x%2B200
Substitute y:
900%28x%2B200%29=1200x
900x%2B180000=1200x
180000=300x
600=x
The rate of the older model jet plane is 600 mph