SOLUTION: At 3:00 p.m. A plane leaves London for Madrid, 1260 km away. At 4 p.m. A plane leaves Madrid to fly to London. The second plane flies 40 kph faster than the first. If the planes pa

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: At 3:00 p.m. A plane leaves London for Madrid, 1260 km away. At 4 p.m. A plane leaves Madrid to fly to London. The second plane flies 40 kph faster than the first. If the planes pa      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 894707: At 3:00 p.m. A plane leaves London for Madrid, 1260 km away. At 4 p.m. A plane leaves Madrid to fly to London. The second plane flies 40 kph faster than the first. If the planes pass each other at 4:30 p.m. What is the speed of each plane? Thank you for your help.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = the speed of the 1st plane in km/hr
+s+%2B+40+ = the speed of the 2nd plane in km/hr
----------------------
Between 3 PM and 4 PM, the 1st plane travels
+d+=+s%2A1+
+d+=+s+
----------------
Start a stopwatch when the 2nd plane leaves at 4PM
They are now +1260+-+s+ km apart
---------------------------------
Think of one plane as flying at the sum of their speeds and the
2nd plane standing still
+1260+-+s+=+%28+s+%2B+s+%2B+40+%29%2A%28+1%2F2+%29+
+2520+-+2s+=+2s+%2B+40+
+4s+=+2520+-+40+
+4s+=+2480+
+s+=+620+
+s+%2B+40+=+660+
Their speeds were 620 km/hr and 660 km/hr
-------------------
check answer:
For 1st plane:
(1) +d%5B1%5D+=+620%2A%281%2F2%29+
(1) +d%5B1%5D+=+310+ km
For 2nd plane:
(2) +d%5B2%5D+=+660%2A%281%2F2%29+
(2) +d%5B2%5D+=+330+ km
----------------------
+d%5B1%5D+%2B+d%5B2%5D+=+310+%2B+330+
+d%5B1%5D+%2B+d%5B2%5D+=+640+ km
and
+1260+-+s+=+1260+-+620+
+1260+-+s+=+640+ km
OK