document.write( "Question 378064: a cashier has 20 bills, all of which are $10 or $20 bills. The total value of the money is $330. How many of each type does the cashier have? \n" ); document.write( "
Algebra.Com's Answer #268597 by richard1234(7193)\"\" \"About 
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Let a,b be the number of $10 and $20 bills, respectively. We have the system of equations\r
\n" ); document.write( "\n" ); document.write( "10a + 20b = 330
\n" ); document.write( "a + b = 20 (since there are 20 bills)\r
\n" ); document.write( "\n" ); document.write( "We can multiply the second equation by 10 to obtain 10a + 10b = 200. Substituting into the first equation we have\r
\n" ); document.write( "\n" ); document.write( "(10a + 10b) + 10b = 330
\n" ); document.write( "200 + 10b = 330
\n" ); document.write( "b = 13, a = 7\r
\n" ); document.write( "\n" ); document.write( "So the cashier has seven $10 bills, 13 $20 bills.
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