document.write( "Question 1102184: A pilot flew his single-engine airplane 60 miles with the wind from City A to above City B. He then turned around and flew back to City A against the wind. If the wind was a constant 30 miles per hour, and the total time going and returning was 1.3 hours, find the speed of the plane in still air. \n" ); document.write( "

Algebra.Com's Answer #716829 by josgarithmetic(39627) $\"\"$ $\"About$

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document.write( "                 SPEED      TIME          DISTANCE\r\n" );
document.write( "\r\n" );
document.write( "WWIND            r+30       60/(r+30)     60\r\n" );
document.write( "\r\n" );
document.write( "AGNSTWIND        r-30       60/(r-30)     60\r\n" );
document.write( "\r\n" );
document.write( "TOTAL                         1.3\r\n" );
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\r
\n" ); document.write( "\n" ); document.write( " $\"60%2F%28r%2B30%29%2B60%2F%28r-30%29=13%2F10\"$ \r
\n" ); document.write( "\n" ); document.write( "-\r
\n" ); document.write( "\n" ); document.write( "multiply both sides by $\"10%28r%2B30%29%28r-30%29\"$ ;\r
\n" ); document.write( "\n" ); document.write( " $\"600%28r-30%29%2B600%28r%2B30%29=13%28r%5E2-900%29\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"600r-18000%2B600r%2B1800=13r%5E2-13%2A900\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"1200r=13r%5E2-11700\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"highlight_green%2813r%5E2-1200r-11700=0%29\"$ \r
\n" ); document.write( "\n" ); document.write( "(discriminant, $\"569%2A60%5E2\"$ )\r
\n" ); document.write( "\n" ); document.write( "-\r
\n" ); document.write( "\n" ); document.write( " $\"highlight_green%28r=%281200%2B60%2Asqrt%28569%29%29%2F26%29\"$ \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " $\"highlight%28r=101.2%29\"$ \n" ); document.write( "

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