document.write( "Question 129829: 3) During the first part of a trip, a canoeist travels 82 miles at a certain speed. The canoeist travels 19 miles on the second part of the trip at a speed 5 mph slower. The total time for the trip is 3 hrs. What was the speed on each part of the trip?\r
\n" ); document.write( "\n" ); document.write( "The speed on the first part of the trip was _______ mph.
\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #94798 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Let's use the formula d=r*t\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Since \"a canoeist travels 82 miles at a certain speed\", this means that our first equation is \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"82=rt%5B1%5D\" Notice how I plugged in \"d=82\" and \"t=t%5B1%5D\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Also, since the \"canoeist travels 19 miles on the second part of the trip at a speed 5 mph slower\", the second equation is \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"19=%28r-5%29t%5B2%5D\" Notice how I plugged in \"d=19\" and \"t=t%5B2%5D\". Also, I replaced r with \"r-5\" (since the canoeist traveled 5 mph slower)\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Finally, because the \"total time for the trip is 3 hrs\", the third equation is \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"t%5B1%5D%2Bt%5B2%5D=3\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So we have the three equations\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"82=rt%5B1%5D\" \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"19=%28r-5%29t%5B2%5D\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"t%5B1%5D%2Bt%5B2%5D=3\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "--------------------------\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"82=rt%5B1%5D\" Start with the first equation\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"82%2Fr=t%5B1%5D\" Divide both sides by r to isolate \"t%5B1%5D\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"t%5B1%5D=82%2Fr\" Rearrange the equation\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "--------------------------\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"19=%28r-5%29t%5B2%5D\" Start with the second equation\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"19%2F%28r-5%29=t%5B2%5D\" Divide both sides by \"r-5\" to isolate \"t%5B2%5D\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"t%5B2%5D=19%2F%28r-5%29\" Rearrange the equation\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "------------------------------\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now let's focus on the third equation \"t%5B1%5D%2Bt%5B2%5D=3\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"82%2Fr%2B19%2F%28r-5%29=3\" Plug in \"t%5B1%5D=82%2Fr\" and \"t%5B2%5D=19%2F%28r-5%29\" into the third equation\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"r%28r-5%29%2882%2Fr%2B19%2F%28r-5%29%29=r%28r-5%29%283%29\" Multiply both sides by the LCD \"r%28r-5%29\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"82%28r-5%29%2B19r=3r%28r-5%29\" Distribute and multiply \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"82r-410%2B19r=3r%5E2-15r\" Distribute again \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"82r-410%2B19r-3r%5E2%2B15r=0\" Subtract 3r^2 from both sides. Add 15r to both sides. \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"-3r%5E2%2B116r-410=0\" Combine like terms\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So after using the quadratic formula or a calculator, we get the solutions\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"r=3.93492\" or \"r=34.73175\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "However, since you cannot take 5 mph away from 3.93 mph (you'll get a negative answer if you do), this means that our only answer is \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"r=34.73175\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So the speed on the first part of the trip was about 34.73 mph
\n" ); document.write( "
\n" ); document.write( "
\n" );