document.write( "Question 1043717: The cost of developing pictures is a linear function of the number of pictures ordered. We placed two orders. The first order had 50 pictures and cost $3.75. The second order had 54 pictures and cost $3.95. Find the cost as a function of the number of pictures \n" ); document.write( "

Algebra.Com's Answer #658895 by josmiceli(19441) $\"\"$ $\"About$

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You are given two points on the line:
\n" ); document.write( "( 50,3 )
\n" ); document.write( "( 54,3.95 )
\n" ); document.write( "Let $\"+C+=+f%28n%29+\"$ where $\"+C+\"$ is cost
\n" ); document.write( "and $\"+n+\"$ is the number of pictures ordered
\n" ); document.write( "--------------------------------------
\n" ); document.write( "Use the general point-slope formula
\n" ); document.write( " $\"+%28+C+-+3+%29+%2F+%28+n+-+50+%29+=+%28+3.95+-+3+%29+%2F+%28+54+-+50+%29+\"$
\n" ); document.write( " $\"++%28+C+-+3+%29+%2F+%28+n+-+50+%29+=+.95+%2F+4+\"$
\n" ); document.write( "Multiply both soides by $\"+4%2A%28+n+-+50+%29+\"$
\n" ); document.write( " $\"+4%2A%28+C+-+3+%29+=+.95%2A%28+n+-+50+%29+\"$
\n" ); document.write( " $\"+4C+-+12+=+.95n+-+47.5+\"$
\n" ); document.write( " $\"+4C+=+.95n+-+35.5+\"$
\n" ); document.write( " $\"+C+=+.2375n+-+8.875+\"$
\n" ); document.write( "-----------------------
\n" ); document.write( "check:
\n" ); document.write( "( 50,3 )
\n" ); document.write( " $\"+C+=+.2375n+-+8.875+\"$
\n" ); document.write( " $\"+3+=+.2375%2A50+-+8.875+\"$
\n" ); document.write( " $\"+3+=+11.875+-+8.875+\"$
\n" ); document.write( " $\"+3+=+3+\"$
\n" ); document.write( "------------------------
\n" ); document.write( "( 54, 3.95 )
\n" ); document.write( " $\"+C+=+.2375n+-+8.875+\"$
\n" ); document.write( " $\"+3.95+=+.2375%2A54+-+8.875+\"$
\n" ); document.write( " $\"+3.95+=+12.825+-+8.875+\"$
\n" ); document.write( " $\"+3.95+=+3.95+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );