document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=365373>Question 365373</A>: <I><SPAN STYLE=\"word-break: break-all;\"> i need to come up with a word problem involving a cell phone plan using system of equations. can you help mee? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #260572 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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/cgi-bin/show-face.mpl?user=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=260572\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I assume they want equations that compare the cost of one cell phone company<BR>\n" );
document.write( " with another, for a specific number of minutes used per month.<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Co. A: $40 a month, with 500 free minutes, 10 cents a minute after that<BR>\n" );
document.write( "The equation for this; let m = no. of minutes used: <BR>\n" );
document.write( "C = .10(m - 500) + 40<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Co. B: $25 a month, all minutes cost you 5 cents<BR>\n" );
document.write( "C = .05m + 25<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Say you talk about 20 min a day, which plan would be the best deal?<BR>\n" );
document.write( "30 * 20 = 600 min per month<BR>\n" );
document.write( "Plan A: <BR>\n" );
document.write( "C = .10(600-500) + 40<BR>\n" );
document.write( "C = .10(100) + 40<BR>\n" );
document.write( "C = 10 + 40<BR>\n" );
document.write( "C = $50<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Plan B: <BR>\n" );
document.write( "C = .05(600) + 25<BR>\n" );
document.write( "C = 30 + 25<BR>\n" );
document.write( "C = $55<BR>\n" );
document.write( ":<BR>\n" );
document.write( "So with this scenario, Plan A is best for you<BR>\n" );
document.write( ":<BR>\n" );
document.write( "A good question would be, how many minutes would cost the same with each plan. <BR>\n" );
document.write( "Plan A = Plan B; solve for m<BR>\n" );
document.write( ".10(m-500) + 40 = .05m + 25<BR>\n" );
document.write( ".10m - 50 + 40 = .05m + 25<BR>\n" );
document.write( ".10m - 10 = .05m + 25<BR>\n" );
document.write( ".10m - .05m = 25 + 10<BR>\n" );
document.write( ".05m = 35<BR>\n" );
document.write( "m = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=35%2F.05 ALIGN=MIDDLE  ALT=\"35%2F.05\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "m = 700 minutes<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Substitute 700 for m in each equation, will see they both cost $60<BR>\n" );
document.write( " Greater than 700 min, Plan B will be a better deal for you<BR>\n" );
document.write( "Confirm this by seeing the cost of 800 min for each plan.<BR>\n" );
document.write( ":<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Does this make sense to you? A good thing to know, something that applies<BR>\n" );
document.write( "to decisions you will make in real life, Do you have any questions about this?  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );