document.write( "Question 1117553: In a club there are 90 members.40% are boys.After some time the boys percentage decreased to 28%.calculate how many boys left the club? \n" ); document.write( "

Algebra.Com's Answer #732667 by ikleyn(52945) $\"\"$ $\"About$

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document.write( "I will assume that some boys left the club, but the number of girls remained the same.\r\n" );
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document.write( "40% of 90 is  0.4*90 = 36;  so the number of boys initially in the club was 36.\r\n" );
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document.write( "Let x be the number of boys who left the club.\r\n" );
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document.write( "Then the decreased population of the club became  90-x, and there are 36-x boys now.\r\n" );
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document.write( "The condition says   = 0.28,   or\r\n" );
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document.write( "36-x = 0.28*(90-x) \r\n" );
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document.write( "36-x = 25.2 - 0.28x\r\n" );
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document.write( "36 - 25.2 = x - 0.28\r\n" );
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document.write( "10.8 = 0.72x  ====>  x =  = 15.\r\n" );
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document.write( "Answer.  15 boys left the club.\r\n" );
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