document.write( "Question 534284: Roger bought hamburgers at a cost of $9 per dozen and bagels at a cost of $3 per dozen. He bought a total of 45 dozens and paid a total of $225. How many dozens of hamburgers and how many dozens of bagels did he buy? \n" ); document.write( "

Algebra.Com's Answer #351435 by oberobic(2304) $\"\"$ $\"About$

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h = number of dozens of hamburgers
\n" ); document.write( "9h = cost of the hamburgers
\n" ); document.write( "b = number of dozens of bagels
\n" ); document.write( "3b = cost of the bagels
\n" ); document.write( ".
\n" ); document.write( "h + b = 45
\n" ); document.write( "so
\n" ); document.write( "h = 45-b
\n" ); document.write( "and
\n" ); document.write( "b = 45-h
\n" ); document.write( ".
\n" ); document.write( "9h + 3b = 225
\n" ); document.write( ".
\n" ); document.write( "Multiply the first equation by 3.
\n" ); document.write( ".
\n" ); document.write( "3h + 3b = 135
\n" ); document.write( "9h + 3b = 225
\n" ); document.write( "--------------
\n" ); document.write( "-6h = -90
\n" ); document.write( ".
\n" ); document.write( "h = -90/-6
\n" ); document.write( "h = 15
\n" ); document.write( ".
\n" ); document.write( "b = 45-15
\n" ); document.write( "b = 30
\n" ); document.write( ".
\n" ); document.write( "Answer: 15 dozen hamburgers and 30 dozen bagels.
\n" ); document.write( ".
\n" ); document.write( "Check the cost.
\n" ); document.write( "15*9 + 30*3 = 225
\n" ); document.write( "Correct.
\n" ); document.write( ".
\n" ); document.write( "Done. \n" ); document.write( "

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