document.write( "Question 232372: Joe and Janna leave home at the same time, traveling in opposite directions. Joe drives 45 miles per hour and Janna drives 40 miles per hour. In how many hours will they be 510 miles apart? \n" ); document.write( "

Algebra.Com's Answer #171732 by ptaylor(2198) $\"\"$ $\"About$

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\n" ); document.write( "Distance(d) equals Rate(r) times Time(t) or d-rt; r=d/t and t=d/r\r
\n" ); document.write( "\n" ); document.write( "Approach 1:
\n" ); document.write( "Let t=time to separate by 510mi
\n" ); document.write( "By inspection, we can see that Joe and Janna are separating at the rate of 45+40 or 85 mph. So our equation to solve is:
\n" ); document.write( "510=85t divide each side by t
\n" ); document.write( "t=6 hours-------time it takes for them to separate by 510 mi\r
\n" ); document.write( "\n" ); document.write( "Approach 2
\n" ); document.write( "Let t=time to separate by 510mi
\n" ); document.write( "Distance Joe travels equals 45t
\n" ); document.write( "Distance Janna travels equals 40t
\n" ); document.write( "Now we know that the above two distances must add up to 510 mi, so:
\n" ); document.write( "45t+40t=510
\n" ); document.write( "85t=510-------------------same as before\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Hope this helps--ptaylor \n" ); document.write( "

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