document.write( "Question 1208347: last Christmas, Angel was able to collect 12 bills consisting of 20 bills and 50 bills form her titas and titos. She received a total bill of 390 from them, How many of each bill did Angel received? Using trial and error
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Algebra.Com's Answer #846720 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "last Christmas, Angel was able to collect 12 bills consisting of 20 bills and 50 bills
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\n" ); document.write( "How many of each bill did Angel received? Using trial and error
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\n" ); document.write( "\n" ); document.write( " I will apply \"smart trial and error\", \r
\n" ); document.write( "\n" ); document.write( " in distinction from stupid trial and error.\r
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document.write( "Let assume first that all 12 bills were 20-bills.\r\n" );
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document.write( "Then the total would be 12*20 = 240 monetary units.\r\n" );
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document.write( "         But Angel collected 390 monetary units, \r\n" );
document.write( "    and the difference is 390-240= 150 monetary units.\r\n" );
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document.write( "It means that not all 12 bills were 20-bills - some were 50-bills.\r\n" );
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document.write( "When we mentally replace 20-bill by 50-bill in our head, we add 50-20 = 30 monetary units.\r\n" );
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document.write( "Hence, in order for to compensate the 150 monetary difference, \r\n" );
document.write( "we should make   = 5 replacement.\r\n" );
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document.write( "It tells us that in the real collection Angel had 5 50-bills.\r\n" );
document.write( "The rest were 12-5 = 7 20-bills.\r\n" );
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document.write( "ANSWER.  In her collection, Angel had 7 20-bills and 5 50-bills.\r\n" );
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document.write( "CHECK.  7*20 + 5*50 = 140 + 250 = 390,  total value.    ! correct !\r\n" );
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