document.write( "Question 815142: A motorboat traveling with the current went 35 mi in 3.5 h.Traveling against the current, the boat went 12 mi in 3h.Find the rate of the boat in calm water and the rate of the current. \n" ); document.write( "

Algebra.Com's Answer #490755 by mananth(16946) $\"\"$ $\"About$

You can put this solution on YOUR website!
Find boat speed & current speed Both times given
\n" ); document.write( "
\n" ); document.write( "boat speed =x mph
\n" ); document.write( "current speed =y mph
\n" ); document.write( "against current 3 hours
\n" ); document.write( "with current 3.5 hours
\n" ); document.write( "
\n" ); document.write( "Distance against 12 miles distance with 35 miles
\n" ); document.write( "t=d/r against current -
\n" ); document.write( "12.00 / ( x - y )= 3.00
\n" ); document.write( "3.00 ( x - y ) = 3.50
\n" ); document.write( "3.00 x - 3.00 y = 12.00 ....................1
\n" ); document.write( "
\n" ); document.write( "35.00 / ( x + y )= 3.50
\n" ); document.write( "3.50 ( x + y ) = 35.00
\n" ); document.write( "3.50 x + 3.50 y = 35.00 ...............2
\n" ); document.write( "Multiply (1) by 3.50
\n" ); document.write( "Multiply (2) by 3.00
\n" ); document.write( "we get
\n" ); document.write( "10.50 x + -10.50 y = 42.00
\n" ); document.write( "10.50 x + 10.50 y = 105.00
\n" ); document.write( "21.00 x = 147.00
\n" ); document.write( "/ 21.00
\n" ); document.write( "x = 7.00 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1) y
\n" ); document.write( "3.00 x -3.00 y = 12.00
\n" ); document.write( "21.00 -3.00 -21.00 = 12.00
\n" ); document.write( "-3.00 y = 12.00
\n" ); document.write( "-3.00 y = -9.00 mph
\n" ); document.write( " y = 3.00
\n" ); document.write( "boat speed 7.00 mph
\n" ); document.write( "current speed 3.00 mph
\n" ); document.write( " \n" ); document.write( "

\n" );