document.write( "Question 672207: A boat travels upstream 60 miles in 4 hours. The return trip going downstream takes 2 hours. Find the rate of the boat in still water and the rate of the current? \n" ); document.write( "

Algebra.Com's Answer #417840 by mananth(16946) $\"\"$ $\"About$

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Boat speed =x mph
\n" ); document.write( "current speed =y mph
\n" ); document.write( "againstcurrent x-y 4 hours
\n" ); document.write( "with current x+y 2 hours
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\n" ); document.write( "Distance = 60 miles distance= 60
\n" ); document.write( "t=d/r against current
\n" ); document.write( "60.00 / ( x - y )= 4.00
\n" ); document.write( "
\n" ); document.write( "4.00 x -4.00 y = 60.00 ....................1
\n" ); document.write( "downstream
\n" ); document.write( "60.00 / ( x + y )= 2.00
\n" ); document.write( "2.00 ( x + y ) = 60.00
\n" ); document.write( "2.00 x + 2.00 y = 60.00 ...............2
\n" ); document.write( "Multiply (1) by 1.00
\n" ); document.write( "Multiply (2) by 2.00
\n" ); document.write( "we get y
\n" ); document.write( "4.00 x -4.00 y = 60.00
\n" ); document.write( "4.00 x + 4.00 = 120.00
\n" ); document.write( "8.00 x = 180.00
\n" ); document.write( "/ 8.00
\n" ); document.write( "x = 22.5 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1) y
\n" ); document.write( "4 x -4 y = 60
\n" ); document.write( "90 -4 -90 = 60
\n" ); document.write( "-4 y = 60
\n" ); document.write( "-4 y = -30 mph
\n" ); document.write( " y = 7.5
\n" ); document.write( " Boat 22.5 mph
\n" ); document.write( " current 7.5 mph
\n" ); document.write( " \n" ); document.write( "

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