document.write( "Question 1194794: The credit remaining on a phone card (in dollars) is a linear function of the total calling time made with the card (in minutes). The remaining credit after 20 minutes of calls is $21.80, and the remaining credit after 33 minutes of calls is $19.72 . What is the remaining credit after 40 minutes of calls? \n" ); document.write( "

Algebra.Com's Answer #827108 by ikleyn(52934) $\"\"$ $\"About$

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\n" ); document.write( "The credit remaining on a phone card (in dollars) is a linear function
\n" ); document.write( "of the total calling time made with the card (in minutes).
\n" ); document.write( "The remaining credit after 20 minutes of calls is $21.80,
\n" ); document.write( "and the remaining credit after 33 minutes of calls is $19.72 .
\n" ); document.write( "What is the remaining credit after 40 minutes of calls?
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document.write( "From the post, the price for one minute call is\r\n" );
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document.write( "     = 0.16 dollars.\r\n" );
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document.write( "So, we take the amount at the credit card of $21.80 after 20 minutes, \r\n" );
document.write( "and subtract from it the cost of (40-20) = 20 minutes\r\n" );
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document.write( "    21.80 - 20*0.16 = 18.60.\r\n" );
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document.write( "ANSWER.  The remaining credit after 40 minutes of calls is $18.60.\r\n" );
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