document.write( "Question 391268: Suppose you write a book. The printer charges $4 per book to print it, and you spend $3500.00 on advertising. You must sell the book for $15.00 a copy. How many copies must you sell so that your income from the sales is greater than your total cost? \n" ); document.write( "

Algebra.Com's Answer #277561 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"c\"$ = costs
\n" ); document.write( "Let $\"b\"$ = number of books sold
\n" ); document.write( "given:
\n" ); document.write( " $\"c+=+4b+%2B+3500\"$
\n" ); document.write( "--------------
\n" ); document.write( " $\"15b+%3E+4b+%2B+3500\"$
\n" ); document.write( " $\"11b+%3E+3500\"$
\n" ); document.write( " $\"b+%3E+318\"$
\n" ); document.write( "You must sell 319 books
\n" ); document.write( "check answer:
\n" ); document.write( " $\"15b+%3E+4b+%2B+3500\"$
\n" ); document.write( " $\"15%2A319+%3E+4%2A319+%2B+3500\"$
\n" ); document.write( " $\"4785+%3E+1276+%2B+3500\"$
\n" ); document.write( " $\"4785+%3E+4776\"$
\n" ); document.write( "OK
\n" ); document.write( "and with $\"b+=+318\"$
\n" ); document.write( " $\"15%2A318+%3E+4%2A318+%2B+3500\"$
\n" ); document.write( " $\"4770+%3E+1272+%2B+3500\"$
\n" ); document.write( " $\"4770+%3E+4772\"$ -not true
\n" ); document.write( "So, 318 is too small \n" ); document.write( "

\n" );