document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=828718>Question 828718</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Ned’s bookstore in Berkeley made a profit of $1137.70 when 71 students bought textbooks at the <BR>\n" );
document.write( "store.  When 86 students bought textbooks, they made a profit of $1488.70.  <BR>\n" );
document.write( "a)  Write a linear function P(x) relating profit to the number of students.  <BR>\n" );
document.write( "b)  What is the variable profit for the store?  What is the fixed cost?<BR>\n" );
document.write( "c)  How many students need to shop at Ned’s for the store to “break even” (profit of $0)? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #499466 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39620)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=499466\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The description contains two ordered pairs of points.\r<BR>\n" );
document.write( "\n" );
document.write( "(students, profit):<BR>\n" );
document.write( "(71,1137) and (86,1488.7).\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "The two points define a line.  Slope-intercept form is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=mx%2Bb ALIGN=MIDDLE  ALT=\"y=mx%2Bb\"   DISABLED_style= \"max-width:90%; height:auto;\" >, and solving for b gives <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=b=y-mx ALIGN=MIDDLE  ALT=\"b=y-mx\"   DISABLED_style= \"max-width:90%; height:auto;\" >.  Compute the slope, m.  Use either point to compute b.  Now restate the equation for the line using m and b values found.  In your example, you want <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y=P%28x%29 ALIGN=MIDDLE  ALT=\"y=P%28x%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.  Do all that and you have answer for (a).\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "(b) seems unclear, but it may be directly related to or the same as (c).  Question part (c) essentially is asking for the x intercept.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "Back to (b) again, the variable profit should be P(x).  This is a variable.  I FEEL that \"fixed cost\" is the y-intercept. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );