document.write( "Question 336593: A boat travels 12 km. upstream from town A to town B in 6 hours. The boat
\n" ); document.write( "then travels downstream from town B to town C, which is 8 km. further downstream
\n" ); document.write( "from A in 5 hours. What is the speed of the boat in still water? \n" ); document.write( "
Algebra.Com's Answer #241255 by mananth(16946)\"\" \"About 
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let the speed of boat in still water be x km/h
\n" ); document.write( "speed of current = y km/h\r
\n" ); document.write( "\n" ); document.write( "..
\n" ); document.write( "distance =12 km
\n" ); document.write( "speed = x-y
\n" ); document.write( "time = 12/(x-y)
\n" ); document.write( "..
\n" ); document.write( "downstream
\n" ); document.write( "distance = 20km
\n" ); document.write( "speed = x+y
\n" ); document.write( "time = 20/x+y
\n" ); document.write( "..
\n" ); document.write( "12/(x-y)= 6
\n" ); document.write( "20/(x+y)= 5
\n" ); document.write( "6x-6y=12
\n" ); document.write( "x-y=2..................1
\n" ); document.write( "..
\n" ); document.write( "5x+5y= 20
\n" ); document.write( "x+y=4..................2
\n" ); document.write( "add 1 & 2
\n" ); document.write( "2x=6
\n" ); document.write( "divide by 2
\n" ); document.write( "x=3 speed of boat in still water
\n" ); document.write( "x-y=2
\n" ); document.write( "3-y=2
\n" ); document.write( "y=1 current speed
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