document.write( "Question 1098057: A student has to sell 2 books from a collection 25 biology,
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Algebra.Com's Answer #712470 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "A student has to sell 2 books from a collection 25 biology,
\n" ); document.write( "21 mathematics, and 14 chemistry books. How many choices are
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\n" ); document.write( "\n" ); document.write( "a. both books are to be on the same subject?
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document.write( "25 biology books Choose 2        <-- 25C2 ways\r\n" );
document.write( "      or                             plus\r\n" );
document.write( "21 mathematics books Choose 2    <-- 21C2 ways\r\n" );
document.write( "      or                             plus \r\n" );
document.write( "14 chemistry books Choose 2      <-- 14C2 ways\r\n" );
document.write( "      \r\n" );
document.write( "25C2 + 21C2 + 14C2 = 300 + 210 + 91 = 601 ways.\r\n" );
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document.write( "Case 1:  Choose a biology book and a mathematics book.\r\n" );
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document.write( "Choose the biology book any of 25 ways.\r\n" );
document.write( "Choose the mathematics book any of 21 ways.\r\n" );
document.write( "That's (25)(21) ways.\r\n" );
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document.write( "Plus\r\n" );
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document.write( "Case 2:  Choose a biology book and a chemistry book.\r\n" );
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document.write( "Choose the biology book any of 25 ways.\r\n" );
document.write( "Choose the chemistry book any of 14 ways.\r\n" );
document.write( "That's (25)(14) ways.\r\n" );
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document.write( "Plus\r\n" );
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document.write( "Case 3:  Choose a mathematics book and a chemistry book.\r\n" );
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document.write( "Choose the mathematics book any of 21 ways.\r\n" );
document.write( "Choose the chemistry book any of 14 ways.\r\n" );
document.write( "That's (21)(14) ways.\r\n" );
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document.write( "Answer:  (25)(21) + (25)(14) + (21)(14) = 525 + 350 + 294 = 1169 ways.\r\n" );
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document.write( "Edwin
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