document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1127211>Question 1127211</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An invoice clerk receives a bill $37.50 for ten blank ledger books and three special filing trays .on phoning the supplier ( after discovering the order had been written incorrectly), the clerk agrees to return three of the ledger books in return for the supplier sending an extra filing tray . Given that there willl be extra $2.50 to pay and that there is 10% discount for orders of 10 ledger books or more ;<BR>\n" );
document.write( "a. Derive a linear equation in x and y to represent the components of the original revised invoices, where x is the price of a single ledger book and y is the price of a filling tray.<BR>\n" );
document.write( "b. Solve the two equation simultaneously for x and y  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #743683 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=743683\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> An invoice clerk receives a bill $37.50 for ten blank ledger books and three special filing trays.<BR>\n" );
document.write( " On phoning the supplier ( after discovering the order had been written incorrectly), the clerk agrees to return three of the ledger books in return for the supplier sending an extra filing tray.<BR>\n" );
document.write( " Given that there will be extra $2.50 to pay and that there is 10% discount for orders of 10 ledger books or more;<BR>\n" );
document.write( ":<BR>\n" );
document.write( "a. Derive a linear equation in x and y to represent the components of the original & revised invoices, where x is the price of a single ledger book and y is the price of a filling tray.<BR>\n" );
document.write( "The original bill had a 10% discount on 10 ledgers, therefore the paid for 9<BR>\n" );
document.write( "9x + 3y = 37.50<BR>\n" );
document.write( "The 2nd bill was $2.50 more. 3 ledgers were returned, 1 tray added, therefore:<BR>\n" );
document.write( "7x + 4y = 40<BR>\n" );
document.write( "b. Solve the two equation simultaneously for x and y <BR>\n" );
document.write( "9x + 3y = 37.50<BR>\n" );
document.write( "7x + 4y = 40.00<BR>\n" );
document.write( "multiply the 1st equation by 4, the 2nd equation by 3<BR>\n" );
document.write( "36x + 12y = 150<BR>\n" );
document.write( "21x + 12y = 120<BR>\n" );
document.write( "-----------------subtraction eliminates y, find x<BR>\n" );
document.write( "15x + 0 = 30<BR>\n" );
document.write( "x = 30/15<BR>\n" );
document.write( "x = $2.00 for ledgers<BR>\n" );
document.write( "Use the 2nd original equation to find y<BR>\n" );
document.write( "7(2) + 4y = 40<BR>\n" );
document.write( "4y = 40 - 14<BR>\n" );
document.write( "y = 26/4<BR>\n" );
document.write( "y = $6.50 for trays<BR>\n" );
document.write( ":<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Check solutions in the 1st original equation<BR>\n" );
document.write( "9(2) + 3(6.50) = <BR>\n" );
document.write( "18 + 19.50 = 37.50 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );