SOLUTION: Two planes leaving O'hare Airport in Chicago at the same time.One flies directly east at 540 mph. The other flies directly west at 720 mph. How long will i take them to be 1890 mil

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Two planes leaving O'hare Airport in Chicago at the same time.One flies directly east at 540 mph. The other flies directly west at 720 mph. How long will i take them to be 1890 mil      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 950088: Two planes leaving O'hare Airport in Chicago at the same time.One flies directly east at 540 mph. The other flies directly west at 720 mph. How long will i take them to be 1890 miles apart?
Found 3 solutions by josmiceli, brysca, Alan3354:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = the distance traveled
by the slower plane until they are
+1890+ mi apart
Let +t+ = the time in hours for them
to be +1890+ mi apart
---------------------------
Equation for the slower plane:
(1) +d+=+540t+
Equation for faster plane:
(2) +1890+-+d+=+720t+
----------------------
Substitute (1) into (2)
(2) +1890+-+540t+=+720t+
(2) +1260t+=+1890+
(2) +t+=+1.5+
In 1.5 hrs they will be 1890 mi apart
----------------
check:
(1) +d+=+540%2A1.5+
(1) +d+=+810+
and
(2) +1890+-+d+=+720t+
(2) +1890+-+810+=+720%2A1.5+
(2) +1080+=+1080+
OK

Answer by brysca(112) About Me  (Show Source):
You can put this solution on YOUR website!
solution posted below
.
hope this helps!

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Two planes leaving O'hare Airport in Chicago at the same time.One flies directly east at 540 mph. The other flies directly west at 720 mph. How long will i take them to be 1890 miles apart?
=====================
Going in opposite directions the speeds are added.
540 + 720 = 1260 mi/hr
----------
d = r*t
t = d/r = 1890/1260
t = 1.5 hours