document.write( "Question 962688: The current of a river moves at 3 miles per hour. It takes a boat a total of 3 hours to travel 12 miles upstream, against the current, and return the same distance traveling downstream, with the current. What is the boat’s rate in still water? \n" ); document.write( "
Algebra.Com's Answer #588259 by Murthy(22)\"\" \"About 
You can put this solution on YOUR website!
Let 'x' be the speed of the boat in miles per hour in still water\r
\n" ); document.write( "\n" ); document.write( "During upstream relative speed of the boat will be (x-3) miles per hour\r
\n" ); document.write( "\n" ); document.write( "During downstream relative speed of the boat will be (x+3) miles per hour\r
\n" ); document.write( "\n" ); document.write( "total time = time taken (upstream)+ time taken (downstream)\r
\n" ); document.write( "\n" ); document.write( "3= distance/(upstream speed)+ distance/(dowmstream speed)\r
\n" ); document.write( "\n" ); document.write( "12/(x-3)+12/(x+3)=3\r
\n" ); document.write( "\n" ); document.write( "=x^2-8x-9=0\r
\n" ); document.write( "\n" ); document.write( "x=9 miles /hour\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
\n" );