document.write( "Question 1016199: cindy has 17 bills in her wallet. some are $10 bills and some are $20 bills. the total value of the bills are $230. how many $10 bills and how many $20 bills does she have? \n" ); document.write( "

Algebra.Com's Answer #632630 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "cindy has 17 bills in her wallet. some are $10 bills and some are $20 bills. the total value of the bills are $230.
\n" ); document.write( "how many $10 bills and how many $20 bills does she have?
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document.write( "Let x = # of $10 bills, and y = # of $20 bills.\r\n" );
document.write( "Then you have the system of two equations in two unknowns\r\n" );
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document.write( "  x +   y =  17,   (1)\r\n" );
document.write( "10x + 20y = 230.   (2)\r\n" );
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document.write( "Express x via y from equation (1): x = 17 - y, and substitute it into equation (2). You will get a single equation for y\r\n" );
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document.write( "10*(17-y) + 20y = 230.\r\n" );
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document.write( "Now simplify and solve:\r\n" );
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document.write( "170 - 10y + 20y = 230,\r\n" );
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document.write( "10y = 230 - 170 = 60.\r\n" );
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document.write( "y =  = 6.\r\n" );
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document.write( "Then x = 17 - y = 17 - 6 = 11.\r\n" );
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document.write( "Answer. 11 $10 bills and 6 $20 bills.\r\n" );
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