document.write( "Question 567285: A boat travels 500 miles downstream and back. The trip downstream took 25 hours. The trip back upstream took 50 hours. What is the speed of the boat? What is the speed of the current in the river? \n" ); document.write( "

Algebra.Com's Answer #366498 by mananth(16946) $\"\"$ $\"About$

You can put this solution on YOUR website!
Boat speed =x mph
\n" ); document.write( "current speed =y mph
\n" ); document.write( "against current x-y 50.00 hours
\n" ); document.write( "with current x+y 20.00 hours
\n" ); document.write( "
\n" ); document.write( "Distance = same= 500 km
\n" ); document.write( "t=d/r
\n" ); document.write( "500 / ( x - y )= 50.00
\n" ); document.write( "50 ( x - y ) = 500.00
\n" ); document.write( "50 x -50 y = 500 ....................1
\n" ); document.write( "500 / ( x + y )= 20.00
\n" ); document.write( "20.00 ( x + y ) = 500
\n" ); document.write( "20.00 x + 20.00 y = 500 ...............2
\n" ); document.write( "Multiply (1) by 2
\n" ); document.write( "Multiply (2) by 5
\n" ); document.write( "we get
\n" ); document.write( "100 x -100 y = 1000
\n" ); document.write( "100 x + 100 y = 2500
\n" ); document.write( "200 x = 3500
\n" ); document.write( "/ 200
\n" ); document.write( "x = 17.5 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "50 x -50 y = 500
\n" ); document.write( "875 -50 y = 500
\n" ); document.write( "-50 y = 500 -875
\n" ); document.write( "-50 y = -375
\n" ); document.write( " y = 7.5
\n" ); document.write( "The speed of Boat = 17.5 mph
\n" ); document.write( "The speed of current = 7.5 mph
\n" ); document.write( "m.ananth@hotmail.ca
\n" ); document.write( " \n" ); document.write( "

\n" );