document.write( "Question 1144743: A boat travels 28 km upstream in 7 hours. It travels 48 km downstream in 4 hours. Find the speed of the boat and the speed of the stream. \n" ); document.write( "
Algebra.Com's Answer #765953 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
A boat travels 28 km upstream in 7 hours.
\n" ); document.write( " It travels 48 km downstream in 4 hours.
\n" ); document.write( " Find the speed of the boat and the speed of the stream.
\n" ); document.write( ":
\n" ); document.write( "let s = speed of boat in still water
\n" ); document.write( "let c = speed of the current
\n" ); document.write( "then
\n" ); document.write( "(s-c) = speed up stream
\n" ); document.write( "(s+c) = speed down stream
\n" ); document.write( ":
\n" ); document.write( "Write an distance equation for each way. Dist = time * speed
\n" ); document.write( "7(s-c) = 28
\n" ); document.write( "4(s+c) = 48
\n" ); document.write( "Simplify these equations, divide the 1st by 7 and the 2nd by 4
\n" ); document.write( "s - c = 4
\n" ); document.write( "s + c = 12
\n" ); document.write( "---------------addition eliminates c find s
\n" ); document.write( "2s + 0 = 16
\n" ); document.write( "s = 16/2
\n" ); document.write( "s = 8 km/h boat speed in still water
\n" ); document.write( "then
\n" ); document.write( "8 - c = 4
\n" ); document.write( "-c = 4 - 8
\n" ); document.write( "-c = -4
\n" ); document.write( "c = 4 km/hr is the speed of the current
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check this in the original equations
\n" ); document.write( "7(8-4) = 28
\n" ); document.write( "4(8+4) = 48
\n" ); document.write( " \n" ); document.write( "
\n" );