document.write( "Question 173469: Carlos leaves LA on a cross country car trip at 8 AM, he is going 50 mph; Juanita plans to do the same but leaves at 9 AM and travels 60 mph, develop a diagram or table to determine at what time Juanita will pass Carlos \n" ); document.write( "
Algebra.Com's Answer #128345 by josmiceli(19441)\"\" \"About 
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For both of them, \"d+=+r%2At\", where
\n" ); document.write( "\"d\"= distance
\n" ); document.write( "\"r\"= rate
\n" ); document.write( "\"t\"= time
\n" ); document.write( "So, for Carlos,
\n" ); document.write( "\"d%5Bc%5D+=+r%5Bc%5D%2At%5Bc%5D\"
\n" ); document.write( "And for Juanita,
\n" ); document.write( "\"d%5Bj%5D+=+r%5Bj%5D%2At%5Bj%5D\"
\n" ); document.write( "----------------------
\n" ); document.write( "The chart would look like this:
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\n" ); document.write( "Distances -- rates -- times
\n" ); document.write( "-------------------------------
\n" ); document.write( " -- d[c] -- -- r[c] -- -- t[c]
\n" ); document.write( " -- d[j] -- -- r[j] -- -- t[j]
\n" ); document.write( "--------------------------------
\n" ); document.write( "Now I can repace some of these variables
\n" ); document.write( "with things that I know about them
\n" ); document.write( "For instance, \"d%5Bc%5D+=+d%5Bj%5D\" because
\n" ); document.write( "the distance is from LA to the place
\n" ); document.write( "where they meet. I'll call them both \"d\"
\n" ); document.write( "-------------------------------
\n" ); document.write( "Distances -- rates -- times
\n" ); document.write( "-------------------------------
\n" ); document.write( " -- d -- -- r[c] -- -- t[c]
\n" ); document.write( " -- d -- -- r[j] -- -- t[j]
\n" ); document.write( "--------------------------------
\n" ); document.write( "Carlos travels 50 mi/hr and Juanita travels 60 mi/hr, so
\n" ); document.write( "-------------------------------
\n" ); document.write( "Distances -- rates -- times
\n" ); document.write( "-------------------------------
\n" ); document.write( " -- d -- -- 50 -- -- t[c]
\n" ); document.write( " -- d -- -- 60 -- -- t[j]
\n" ); document.write( "--------------------------------
\n" ); document.write( "Juanita leaves LA an hour later, so she has to cover the same
\n" ); document.write( "distance in 1 hour less time, so
\n" ); document.write( "-------------------------------
\n" ); document.write( "Distances -- rates -- times
\n" ); document.write( "-------------------------------
\n" ); document.write( " -- d -- -- 50 -- --t[c]
\n" ); document.write( " -- d -- -- 60 -- --t[c] - 1
\n" ); document.write( "--------------------------------
\n" ); document.write( "Now I can use this to find out when Juanita will pass Carlos.
\n" ); document.write( "The problem doesn't ask for it, but I'll do the algebra
\n" ); document.write( "\"d+=+r%2At\" for both of them, so
\n" ); document.write( "(1) \"d+=+50t%5Bc%5D\"
\n" ); document.write( "\"d+=+60%2A%28t%5Bc%5D+-+1%29\"
\n" ); document.write( "(2) \"d+=+60t%5Bc%5D+-+60\"
\n" ); document.write( "The \"d\"s are the same in (1) and (2),
\n" ); document.write( "so I'll set them equal to eachother
\n" ); document.write( "(3) \"50t%5Bc%5D+=+60t%5Bc%5D+-+60\"
\n" ); document.write( "\"10t%5Bc%5D+=+60\"
\n" ); document.write( "\"t%5Bc%5D+=+6\"
\n" ); document.write( "And, since \"t%5Bj%5D+=+t%5Bc%5D+-+1\",
\n" ); document.write( "\"t%5Bj%5D+=+6+-+1\"
\n" ); document.write( "\"t%5Bj%5D+=+5\"
\n" ); document.write( "Carlos left LA at 8AM, so 6 hours later,
\n" ); document.write( "it would have been 2PM
\n" ); document.write( "Juanita left LA at 9AM, so 5 hours later,
\n" ); document.write( "It would have been 2PM, which is when she passed him
\n" ); document.write( "check answer:
\n" ); document.write( "The distances must be the same, so
\n" ); document.write( "(1) \"d+=+50t%5Bc%5D\"
\n" ); document.write( "\"d+=+50%2A6\"
\n" ); document.write( "\"d+=+300\" mi
\n" ); document.write( "(2) \"d+=+60t%5Bc%5D+-+60\"
\n" ); document.write( "\"d+=+60%2A6+-+60\"
\n" ); document.write( "\"d+=+360+-+60\"
\n" ); document.write( "\"d+=+300\" mi
\n" ); document.write( "OK
\n" ); document.write( "
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