document.write( "Question 336152: When making a telephone call using a calling card, a call lasting 6 minutes costs $2.90. A call lasting 16 minutes cost $6.90. Find a linear function that relates the cost, C, of a making a call length, X, of the call, treating length of the call as the independent variable. \n" ); document.write( "
Algebra.Com's Answer #241046 by stanbon(75887)\"\" \"About 
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When making a telephone call using a calling card, a call lasting 6 minutes costs $2.90. A call lasting 16 minutes cost $6.90. Find a linear function that relates the cost, C, of a making a call length, X, of the call, treating length of the call as the independent variable.
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\n" ); document.write( "You have two points : (6,2.9) and (16,6.9)
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\n" ); document.write( "slope = (6.9-2.9)/(16-6) = 4/10 = 2/5
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\n" ); document.write( "Linear Form: cost = (slope)(length of call)+b
\n" ); document.write( "Solve for \"b\":
\n" ); document.write( "2.9 = (2/5)(6)+b
\n" ); document.write( "b = 2.9-(2/5)(6)
\n" ); document.write( "b = 0.5
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\n" ); document.write( "Equation:
\n" ); document.write( "cost = (2/5)x + (1/2)
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "
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