document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=28365>Question 28365</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A fire is reported at a chemical plant on the east side of the city.  The fire engine travels an average of 38 mile per hour.  It takes the engine 15 minutes to get to the chemical plant.  How far away is the chemical plant?<BR>\n" );
document.write( "A. 7.1 miles<BR>\n" );
document.write( "B. 7.4 miles<BR>\n" );
document.write( "C. 8.6 miles<BR>\n" );
document.write( "D. 9.2 miles<BR>\n" );
document.write( "E. 9.5 miles<BR>\n" );
document.write( "I need to figure out how to solve this problem step by step please. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #15414 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=15414\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> First, any word problem will have quantities expressed in units.<BR>\n" );
document.write( "Time, distance, temperature all have their units. A long time ago, in<BR>\n" );
document.write( "high school physics, I learned how to cancel units in an equation.<BR>\n" );
document.write( "When all done cancelling, you always get minutes = minutes<BR>\n" );
document.write( "or feet = feet, etc. Then you know you handled the units correctly.<BR>\n" );
document.write( "The last sentence says \"how far\" You know the answer will have units of distance, and sure enough, the choices are all in \"miles\".<BR>\n" );
document.write( "distance = rate x time<BR>\n" );
document.write( "There aren't many formulas you should memorize, but that is one of them.<BR>\n" );
document.write( "Now the thing about cancelling units<BR>\n" );
document.write( "Let d = the distance to the chemical plant in miles<BR>\n" );
document.write( "The average rate is 38 miles/hour<BR>\n" );
document.write( "The time to the chemical plant is 15 minutes<BR>\n" );
document.write( "the formula<BR>\n" );
document.write( "d miles = 38 miles/hour x 15 minutes<BR>\n" );
document.write( "There are \"miles\" on both sides - that's good. but on the right side,<BR>\n" );
document.write( "hours and minutes don't cancel<BR>\n" );
document.write( "By cancelling I mean minutes / minutes cancel<BR>\n" );
document.write( "You've got minutes / hours<BR>\n" );
document.write( "The trick is to insert the fraction <BR>\n" );
document.write( "1 hour / 60 minutes as a factor on the right side<BR>\n" );
document.write( "That doesn't change anything because 1 hour = 60 minutes and thats<BR>\n" );
document.write( "the same as 1/1 or 6/6 or a/a they all = 1<BR>\n" );
document.write( "So now<BR>\n" );
document.write( "d miles = 38 miles/hour x 15 minutes x 1 hour / 60 minutes<BR>\n" );
document.write( "This is perfect- the right side has hours/hours and minutes/minutes,<BR>\n" );
document.write( "leaving only miles on the right side<BR>\n" );
document.write( "miles = miles<BR>\n" );
document.write( "so, leaving out the units, <BR>\n" );
document.write( "d = 38 x 15 x 1/60<BR>\n" );
document.write( "d = 38 / 4<BR>\n" );
document.write( "d = 9.5 miles<BR>\n" );
document.write( "Once you get this cancelling of units, it's a great check to see if<BR>\n" );
document.write( "you've really got the right answer </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );