document.write( "Question 159703: A train travels 180 miles in the same time that a car travels 120 miles. The speed of the train is 20 miles per hour faster than the speed of the car. Find the speed of the train and the speed of the car. Please solve step by step. \n" ); document.write( "
Algebra.Com's Answer #117768 by solver91311(24713)\"\" \"About 
You can put this solution on YOUR website!
We know that \"d=rt\" and therefore \"t=d%2Fr\". Now, if \"d%5Bt%5D\" and \"r%5Bt%5D\" are the distance travelled and the speed of the train, while \"d%5Bc%5D\" and \"r%5Bc%5D\" are the distance travelled and the speed of the car, then:\r
\n" ); document.write( "\n" ); document.write( "We are given that:\r
\n" ); document.write( "\n" ); document.write( "\"d%5Bt%5D=180\",\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"d%5Bc%5D=120\",\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "and \"r%5Bt%5D=r%5Bc%5D%2B20\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Further, we know that the time is the same for both the train's trip and the car's trip.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "For the train: \"t=180%2Fr%5Bt%5D\" or \"t=180%2F%28r%5Bc%5D%2B20%29\" and\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "For the car: \"t=120%2Fr%5Bc%5D\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Since \"t=t\", we can say \"180%2F%28r%5Bc%5D%2B20%29=120%2Fr%5Bc%5D\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Cross-multiply: \"180r%5Bc%5D=120%28r%5Bc%5D%2B20%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Distribute: \"180r%5Bc%5D=120r%5Bc%5D%2B2400\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Add \"-120r%5Bc%5D\" to both sides: \"180r%5Bc%5D-120r%5Bc%5D=2400\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Collect like terms: \"60r%5Bc%5D=2400\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Divide by 60: \"r%5Bc%5D=40\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Compute \"r%5Bt%5D\": \"r%5Bt%5D=r%5Bc%5D%2B20=40%2B20=60\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So the train travels at 60 mph and the car at 40 mph.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Check the answer:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "How long does it take the train to go 180 miles? \"180%2F60=3\" hours\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "How long does it take the car to go 120 miles? \"120%2F40=3\" hours.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "The time is the same so the answer checks.
\n" ); document.write( "
\n" );