document.write( "Question 1136344: A train leaves Little Rock, Arkansas, and travels north at 90 kilometers per hour. Another train leaves at the same time and travels south at 80 kilometers per hour. How long will it take before they are 680 kilometers apart? \n" ); document.write( "

Algebra.Com's Answer #754098 by josmiceli(19441) $\"\"$ $\"About$

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Add their rates of travel
\n" ); document.write( "Let $\"+t+\"$ = time in hrs
\n" ); document.write( " $\"+680+=+%28+90+%2B+80+%29%2At+\"$
\n" ); document.write( " $\"+680+=+170t+\"$
\n" ); document.write( " $\"+t+=+4+\"$
\n" ); document.write( "In 4 hrs they are 680 km apart
\n" ); document.write( "-------------------------------------
\n" ); document.write( "check:
\n" ); document.write( " $\"+d%5B1%5D+=+90%2A4+\"$
\n" ); document.write( " $\"+d%5B1%5D+=+360+\"$
\n" ); document.write( "and
\n" ); document.write( " $\"+d%5B2%5D+=+80%2A4+\"$
\n" ); document.write( " $\"+d%5B2%5D+=+320+\"$
\n" ); document.write( "and
\n" ); document.write( " $\"+d%5B1%5D+%2B+d%5B2%5D+=+360+%2B+320+\"$
\n" ); document.write( " $\"+d%5B1%5D+%2B+d%5B2%5D+=+680+\"$
\n" ); document.write( "OK \n" ); document.write( "

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