document.write( "Question 1088680: Competing in a mini-triathlon, Catherine ran 3 miles in the same amount of time she biked 12 miles. Her average speed on the bike was 18 mph more than her average running speed. What was her running speed? \n" ); document.write( "

Algebra.Com's Answer #702992 by ikleyn(52787) $\"\"$ $\"About$

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document.write( "Let r be her running speed, in miles per hour.\r\n" );
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document.write( "Then her biking speed is (r+18) mph.\r\n" );
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document.write( "The time of running 3 miles was  hours. (= distance/rate)\r\n" );
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document.write( "The time of biking was  hours.    (= distance/rate)\r\n" );
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document.write( "The condition says that \r\n" );
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document.write( " = .\r\n" );
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document.write( "It is your equation. You must solve it to find the unknown r.\r\n" );
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document.write( "I can solve it mentally: r = 6 mph.\r\n" );
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document.write( "If you want to solve it analytically, then multiply both sides by r*(r+18); then simplify. You will get a quadratic equation.\r\n" );
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document.write( "Solve it by factoring or use the quadratic formula.\r\n" );
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document.write( "You just know the answer.\r\n" );
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