document.write( "Question 872026: A boat can travel 20 miles downstream in 2 hours. The same boat can travel 12 miles upstream in 6 hours. Find the speed of the boat in still water and the speed of the current. \n" ); document.write( "
Algebra.Com's Answer #525935 by ankor@dixie-net.com(22740)\"\" \"About 
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A boat can travel 20 miles downstream in 2 hours.
\n" ); document.write( " The same boat can travel 12 miles upstream in 6 hours.
\n" ); document.write( " Find the speed of the boat in still water and the speed of the current.
\n" ); document.write( ":
\n" ); document.write( "Let s = boat speed in still water
\n" ); document.write( "Let c = current speed
\n" ); document.write( "then
\n" ); document.write( "(s+c) = effective speed downstream
\n" ); document.write( "and
\n" ); document.write( "(s-c) = effective speed upstream
\n" ); document.write( ":
\n" ); document.write( "Write a distance equation for each way, dist = time * speed
\n" ); document.write( "2(s+c) = 20
\n" ); document.write( "6(s-c) = 12
\n" ); document.write( "simplify, divide the 1st equation by 2, divide the 2nd equation by 6
\n" ); document.write( "s + c = 10
\n" ); document.write( "s - c = 2
\n" ); document.write( "------------Adding eliminates c, find s
\n" ); document.write( "2s + 0 = 12
\n" ); document.write( "s = 12/2
\n" ); document.write( "s = 6 mph is the speed in still water
\n" ); document.write( "then
\n" ); document.write( "6 + c = 10
\n" ); document.write( "c = 4 mph is the current
\n" ); document.write( ";
\n" ); document.write( ":
\n" ); document.write( "Check solution in the original 1st equation
\n" ); document.write( "2(6+4) = 20\r
\n" ); document.write( "\n" ); document.write( "; \n" ); document.write( "
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