document.write( "Question 558130: A passenger plane flew to moscow and back. The trip there took five hours and the trip back took nine hours. It averaged 144 km/h faster on the trip there than on the return trip. Find the passenger plane's average speed on the outbound trip.\r
\n" ); document.write( "\n" ); document.write( "O.k so I did have a go at it Trying to use a system of equations using the substitution method to eliminate one unknown but it didn't work. I will try and explain what I was playing around with:\r
\n" ); document.write( "\n" ); document.write( "D1 = Distance there D2 = Distance back ( but not sure if I needed this as it is same Distance )
\n" ); document.write( "Average Speed = S \r
\n" ); document.write( "\n" ); document.write( "D1/5 + D2/9 = S\r
\n" ); document.write( "\n" ); document.write( "D1/5 = D2/9+144 ( I tried substituting this in )\r
\n" ); document.write( "\n" ); document.write( "D2/9+144 + D2/9 = S ( then I combined the like terms )\r
\n" ); document.write( "\n" ); document.write( "D2/18+144 = s ( but this is where I realized I had failed as I still had 2 variables.\r
\n" ); document.write( "\n" ); document.write( "Please help me someone I am so bad at word problems and I would love to be confident at them. \r
\n" ); document.write( "\n" ); document.write( "P.S I wasn't sure about which was the outbound trip, I guessed it meant the trip back.\r
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Algebra.Com's Answer #852281 by ikleyn(52847)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "A passenger plane flew to Moscow and back. The trip there took five hours and the trip back took nine hours.
\n" ); document.write( "It averaged 144 km/h faster on the trip there than on the return trip.
\n" ); document.write( "Find the passenger plane's average speed on the outbound trip.
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\n" ); document.write( "\n" ); document.write( "As I read the post by @Theo, I clearly see that his solution is overcomplicated
\n" ); document.write( "and his setup is over-sophisticated. Actually, this problem admits much more simple treatment.
\n" ); document.write( "It is not about a choice of the solution method - it is about how to teach
\n" ); document.write( "young students in a right way. It is impossible to teach them presenting Theo' approach.
\n" ); document.write( "Therefore, I developed and present here a simple solution, which is a standard
\n" ); document.write( "method (or one of standards methods) for this problem.\r
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document.write( "Outbound trip = the trip back (from Moscow).\r\n" );
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document.write( "Trip to Moscow is 5 hours.\r\n" );
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document.write( "The trip back is 9 hours.\r\n" );
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document.write( "Let x be the average speed on the outbound trip (from Moscow), in km/h.\r\n" );
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document.write( "It is the value, which is under the question of the problem.\r\n" );
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document.write( "Then the average speed on the trip to Moscow was (x-144) km/h, according to the problem.\r\n" );
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document.write( "The distance for the flight to Moscow is 5x kilometers  (the product of the time and the speed).\r\n" );
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document.write( "The distance for the returning flight is 9(x-144) kilometers, similarly..\r\n" );
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document.write( "This distances are equal - so, we can write this equation\r\n" );
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document.write( "    5x = 9(x-144).    (1)\r\n" );
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document.write( "Simplify and find x\r\n" );
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document.write( "    5x = 9x - 9*144\r\n" );
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document.write( "    9*144 = 9x - 5x\r\n" );
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document.write( "    9*144 = 4x\r\n" );
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document.write( "    x = (9*144)/4 = 9*36 = 324 kilometers per hour.\r\n" );
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document.write( "ANSWER.  The average speed on the outbound trip was 324 km/h.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved.\r
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\n" ); document.write( "\n" ); document.write( "The solution, which I presented in this my post, follows a standard approach to the problem
\n" ); document.write( "without any sophistications. It provides the most simple and the most straightforward treatment of the problem.\r
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