document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=230078>Question 230078</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A car takes 2 hours less for a journey of 300km, if its speed is increased by 5 km/h from its usual speed. Find its usual speed. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #170444 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=170444\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s ALIGN=MIDDLE  ALT=\"s\"   DISABLED_style= \"max-width:90%; height:auto;\" > = it's usual speed<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t ALIGN=MIDDLE  ALT=\"t\"   DISABLED_style= \"max-width:90%; height:auto;\" > = it's usual time for 300 km journey<BR>\n" );
document.write( "given:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+st ALIGN=MIDDLE  ALT=\"300+=+st\"   DISABLED_style= \"max-width:90%; height:auto;\" > km<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+%28s+%2B+5%29%2A%28t+-+2%29 ALIGN=MIDDLE  ALT=\"300+=+%28s+%2B+5%29%2A%28t+-+2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-------------------------<BR>\n" );
document.write( "This is 2 equations and 2 unknowns, so it's solvable<BR>\n" );
document.write( "Expand (2)<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+%28s+%2B+5%29%2A%28t+-+2%29 ALIGN=MIDDLE  ALT=\"300+=+%28s+%2B+5%29%2A%28t+-+2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+st+%2B+5t+-+2s+-+10 ALIGN=MIDDLE  ALT=\"300+=+st+%2B+5t+-+2s+-+10\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "substitute (1) in (2)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+300+%2B+5t+-+2s+-+10 ALIGN=MIDDLE  ALT=\"300+=+300+%2B+5t+-+2s+-+10\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5t+=+2s+%2B+10 ALIGN=MIDDLE  ALT=\"5t+=+2s+%2B+10\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t+=+%282%2F5%29%2As+%2B+2 ALIGN=MIDDLE  ALT=\"t+=+%282%2F5%29%2As+%2B+2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Plug this back into (1)<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+st ALIGN=MIDDLE  ALT=\"300+=+st\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+s%2A%28%282%2F5%29%2As+%2B+2%29 ALIGN=MIDDLE  ALT=\"300+=+s%2A%28%282%2F5%29%2As+%2B+2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+%282%2F5%29%2As%5E2+%2B+2s ALIGN=MIDDLE  ALT=\"300+=+%282%2F5%29%2As%5E2+%2B+2s\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1500+=+2s%5E2+%2B+10s ALIGN=MIDDLE  ALT=\"1500+=+2s%5E2+%2B+10s\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2s%5E2+%2B+10s+-+1500+=+0 ALIGN=MIDDLE  ALT=\"2s%5E2+%2B+10s+-+1500+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s%5E2+%2B+5s+-+750+=+0 ALIGN=MIDDLE  ALT=\"s%5E2+%2B+5s+-+750+=+0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Solve using quadratic formula<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"s+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=a+=+1 ALIGN=MIDDLE  ALT=\"a+=+1\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=b+=+5 ALIGN=MIDDLE  ALT=\"b+=+5\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=c+=+-750 ALIGN=MIDDLE  ALT=\"c+=+-750\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+%28-5+%2B-+sqrt%28+5%5E2-4%2A1%2A%28-750%29+%29%29%2F%282%2A1%29+ ALIGN=MIDDLE  ALT=\"s+=+%28-5+%2B-+sqrt%28+5%5E2-4%2A1%2A%28-750%29+%29%29%2F%282%2A1%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-5+%2B-+sqrt%28+25+%2B+3000+%29%29%2F2+ ALIGN=MIDDLE  ALT=\"x+=+%28-5+%2B-+sqrt%28+25+%2B+3000+%29%29%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+%28-5+%2B-+sqrt%28+3025+%29%29%2F2+ ALIGN=MIDDLE  ALT=\"s+=+%28-5+%2B-+sqrt%28+3025+%29%29%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+%28-5+%2B-+55%29%2F2+ ALIGN=MIDDLE  ALT=\"s+=+%28-5+%2B-+55%29%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=s+=+25 ALIGN=MIDDLE  ALT=\"s+=+25\"   DISABLED_style= \"max-width:90%; height:auto;\" > (the negative answer can't be used)<BR>\n" );
document.write( "It's usual speed is 25 km/hr<BR>\n" );
document.write( "check answer:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+st ALIGN=MIDDLE  ALT=\"300+=+st\"   DISABLED_style= \"max-width:90%; height:auto;\" > km<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+25t ALIGN=MIDDLE  ALT=\"300+=+25t\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t+=+12 ALIGN=MIDDLE  ALT=\"t+=+12\"   DISABLED_style= \"max-width:90%; height:auto;\" > hrs<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+%28s+%2B+5%29%2A%28t+-+2%29 ALIGN=MIDDLE  ALT=\"300+=+%28s+%2B+5%29%2A%28t+-+2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+%2825+%2B+5%29%2A%2812+-+2%29 ALIGN=MIDDLE  ALT=\"300+=+%2825+%2B+5%29%2A%2812+-+2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+30%2A10 ALIGN=MIDDLE  ALT=\"300+=+30%2A10\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=300+=+300 ALIGN=MIDDLE  ALT=\"300+=+300\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );