document.write( "Question 149572: Audrey has 28 dimes and quarters in her piggy bank with a total value of $4.75. How many of the coins are dimes and how many are quarters? \n" ); document.write( "

Algebra.Com's Answer #109728 by Fombitz(32388) $\"\"$ $\"About$

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Let's call dimes, D, and quarters, Q.
\n" ); document.write( "1. $\"D%2BQ=28\"$ Total number of coins.
\n" ); document.write( "2. $\"0.10%2AD%2B0.25%2AQ=4.75\"$ Total value of coins.
\n" ); document.write( "Let's multiply equation 2 by 100 to get rid of decimals.
\n" ); document.write( "1. $\"D%2BQ=28\"$
\n" ); document.write( "2. $\"10D%2B25Q=475\"$
\n" ); document.write( "Use eq. 1 to solve for D and a function of Q.
\n" ); document.write( "1. $\"D%2BQ=28\"$
\n" ); document.write( " $\"D=28-Q\"$
\n" ); document.write( "Now substitute this expression for D in eq. 2,
\n" ); document.write( "2. $\"10D%2B25Q=475\"$
\n" ); document.write( " $\"10%2828-Q%29%2B25Q=475\"$
\n" ); document.write( "Solve for Q.
\n" ); document.write( " $\"280-10Q%2B25Q=475\"$
\n" ); document.write( " $\"280%2B15Q=475\"$
\n" ); document.write( " $\"15Q=195\"$
\n" ); document.write( " $\"Q=13\"$
\n" ); document.write( "Use eq.1 to solve for D.
\n" ); document.write( " $\"D=28-Q\"$
\n" ); document.write( " $\"D=28-13\"$
\n" ); document.write( " $\"D=15\"$
\n" ); document.write( "Audrey has 15 dimes and 13 quarters. \n" ); document.write( "

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