document.write( "Question 588188: Kathryn row a boat downstream for 40 miles. The return trip upstream took 16 hours longer, If the current flows at 4mph how fast does Kathryn row in still water?\r
\n" ); document.write( "\n" ); document.write( "I am stuck as I cant find an example in my text book with an explanation on how to solve \n" ); document.write( "
Algebra.Com's Answer #374409 by mananth(16949)\"\" \"About 
You can put this solution on YOUR website!
Boat speed = xmph
\n" ); document.write( "current speed = 4mph\r
\n" ); document.write( "\n" ); document.write( "sped with current = x+4 mph
\n" ); document.write( "speed against current = x-4 mph\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "t= d/r
\n" ); document.write( "time taken with current =
\n" ); document.write( "40/(x+4) \r
\n" ); document.write( "\n" ); document.write( "time taken against current = 40/(x-4)\r
\n" ); document.write( "\n" ); document.write( "40/(x-4) =40/(x+4) + 16\r
\n" ); document.write( "\n" ); document.write( "40/(x-4) -40/(x+4) =16\r
\n" ); document.write( "\n" ); document.write( "LCD = (x+4) (x-4)\r
\n" ); document.write( "\n" ); document.write( "multiply by the LCD\r
\n" ); document.write( "\n" ); document.write( "40(x+4) -40(x-4) = 16(x^2-16)\r
\n" ); document.write( "\n" ); document.write( "40x+160-40x+160 = 16x^2-256\r
\n" ); document.write( "\n" ); document.write( "16x^2= 320 +256
\n" ); document.write( "16x^2=576
\n" ); document.write( "x^2= 576/16
\n" ); document.write( "x^2= 36
\n" ); document.write( "x= +/- 6\r
\n" ); document.write( "\n" ); document.write( "speed of boat = 6 mph
\n" ); document.write( " \n" ); document.write( "
\n" );