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Express commuter train #12 leaves the downtown station and travels at an average speed of 50miles per hour towards the north side station, which is 56.75miles away.
\n" ); document.write( " Twelve minutes later, express commuter train #7 leaves the north side station and travels at an average speed of 35 miles per hour towards the downtown station.
\n" ); document.write( " At the moment when the two trains pass each other, how far (in miles) is the #12 train from the downtown station and how long (in minutes) has the #12 train have been traveling?
\n" ); document.write( ":
\n" ); document.write( "Change 12 min to .2 hrs
\n" ); document.write( "let t = travel time of #7 train when they meet
\n" ); document.write( "then
\n" ); document.write( "(t+.2) = travel time of #12 which left 12 min earlier
\n" ); document.write( ":
\n" ); document.write( "Write distance equation dist = speed * time
\n" ); document.write( "#12 dist + #7 dist = 56.75 mi
\n" ); document.write( "50(t+.2) + 35t = 56.75
\n" ); document.write( "50t + 10 + 35t = 56.75
\n" ); document.write( "85t = 56.75 - 10
\n" ); document.write( "t = 46.75/85
\n" ); document.write( "t = .55 hrs is the travel time of #7
\n" ); document.write( "then
\n" ); document.write( ".55 + .2 = .75 hrs is the travel time of #12 when the two trains met
\n" ); document.write( "Find the distance #12 traveled in .75 hr
\n" ); document.write( "50 * .75 = 37.5 mi
\n" ); document.write( "\"At the moment when the two trains pass each other, how far (in miles) is the #12 train from the downtown station and how long (in minutes) has the #12 train have been traveling?\"
\n" ); document.write( "Train # 12 traveled 37.5 mi in 45 min to the meeting point \n" ); document.write( "