document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=824282>Question 824282</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A book store can purchase several calculators for a total cost of $120. If each calculator cost $1 less, the bookstore could purchase 10 additional calculators at the same total cost. How many calculators can be purchased at the regular price? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #496239 by </B><A HREF=/tutors/aboutme.mpl?userid=TimothyLamb><B>TimothyLamb(4379)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=TimothyLamb><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=TimothyLamb><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=496239\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> ---<BR>\n" );
document.write( "x = number of calculators<BR>\n" );
document.write( "y = price<BR>\n" );
document.write( "---<BR>\n" );
document.write( "xy = 120<BR>\n" );
document.write( "(x + 10)(y - 1) = 120<BR>\n" );
document.write( "---<BR>\n" );
document.write( "y = 120/x<BR>\n" );
document.write( "xy - x + 10y - 10 = 120<BR>\n" );
document.write( "x120/x - x + 10*120/x - 10 = 120<BR>\n" );
document.write( "-x + 1200/x - 10 = 0<BR>\n" );
document.write( "-xx + 1200 - 10x = 0<BR>\n" );
document.write( "-xx - 10x + 1200 = 0<BR>\n" );
document.write( "---<BR>\n" );
document.write( "the above quadratic equation is in standard form, with a=-1, b=-10, and c=1200<BR>\n" );
document.write( "---<BR>\n" );
document.write( "to solve the quadratic equation, by using the quadratic formula, copy and paste this:<BR>\n" );
document.write( "-1 -10 1200<BR>\n" );
document.write( "into this solver: https://sooeet.com/math/quadratic-equation-solver.php<BR>\n" );
document.write( "---<BR>\n" );
document.write( "this quadratic has two real roots (the x-intercepts), which are:<BR>\n" );
document.write( "x = -40<BR>\n" );
document.write( "x = 30<BR>\n" );
document.write( "---<BR>\n" );
document.write( "a negative number of calculators doesn't make sense for this problem, so use the positive root:<BR>\n" );
document.write( "---<BR>\n" );
document.write( "answer:<BR>\n" );
document.write( "x = number of calculators = 30<BR>\n" );
document.write( "y = price = $4<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Solve and graph linear equations:<BR>\n" );
document.write( "https://sooeet.com/math/linear-equation-solver.php<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Solve quadratic equations, quadratic formula:<BR>\n" );
document.write( "https://sooeet.com/math/quadratic-formula-solver.php<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Solve systems of linear equations up to 6-equations 6-variables:<BR>\n" );
document.write( "https://sooeet.com/math/system-of-linear-equations-solver.php </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );