SOLUTION: Car A and car B travel towards each other on a 42-km straight highway.Car A travels at a rate of 60 kph while car B travels at a rate of 80 kph.In how many minutes will the 2 cars

Algebra ->  Pythagorean-theorem -> SOLUTION: Car A and car B travel towards each other on a 42-km straight highway.Car A travels at a rate of 60 kph while car B travels at a rate of 80 kph.In how many minutes will the 2 cars       Log On


   

Question 1062633: Car A and car B travel towards each other on a 42-km straight highway.Car A travels at a rate of 60 kph while car B travels at a rate of 80 kph.In how many minutes will the 2 cars meet?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Think of this as one of the cars standing still
and the other traveling at the sum of their speeds
until it meets the other car
Let +t+ = time in hrs until they meet
------------------------------------
+42+=+%28+60+%2B+80+%29%2At+
+42+=+140t+
+t+=+.3+ hrs
Convert hrs to minutes
+.3%2A60+=+18+
They will meet in 18 min
---------------------------
Check answer:
+d%5B1%5D+=+60t+
+d%5B1%5D+=+60%2A.3+
+d%5B1%5D+=+18+ km
and
+d%5B2%5D+=+80t+
+d%5B2%5D+=+80%2A.3+
+d%5B2%5D+=+24++ km
and
+18+%2B+24+=+42+ km
OK