document.write( "Question 1062361: a pizzeria sells three sizes of pizza: small, medium, and large. the pizzas sell for $9, $10, and $13, respectively. one evening they sold 21 pizzas and received $220. if they sold 1 more medium than large pizzas, how many of each size did they sell? \n" ); document.write( "

Algebra.Com's Answer #677259 by ikleyn(52778) $\"\"$ $\"About$

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\n" ); document.write( "a pizzeria sells three sizes of pizza: small, medium, and large. the pizzas sell for $9, $10, and $13, respectively.
\n" ); document.write( "one evening they sold 21 pizzas and received $220. if they sold 1 more medium than large pizzas, how many of each size did they sell?
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document.write( "Let S = # small pizza; L = # large pizza.\r\n" );
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document.write( "Then you have these two equations:\r\n" );
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document.write( " S + (L +1) + L    =  21,    (1)\r\n" );
document.write( "9S + L(10+13) + 10 = 220.    (2)\r\n" );
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document.write( "Simplify and write in the standard form:\r\n" );
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document.write( " S +  2L =  20,              (1')\r\n" );
document.write( "9S + 23L = 210.              (2')\r\n" );
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document.write( "From (1'), express S = 20 - 2L and substitute it into (2) replacing S:\r\n" );
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document.write( "9*(20-2L) + 23L = 210,\r\n" );
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document.write( "180 - 18L + 23L = 210,\r\n" );
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document.write( "5L = 210 - 180,\r\n" );
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document.write( "5L = 30  --->  L = 6.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Answer. 6 large pizzas; 7 medium pizzas and (21-6-7) = 8 small pizzas.\r
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