document.write( "Question 454466: with the current, which is 2 mph, i can travel 48 miles in my boat.
\n" ); document.write( "Against the current, it takes 2 more hours to travel the same 48 miles.
\n" ); document.write( "what is the speed of my boat in still water? \n" ); document.write( "
Algebra.Com's Answer #312079 by ankor@dixie-net.com(22740)\"\" \"About 
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with the current, which is 2 mph, i can travel 48 miles in my boat.
\n" ); document.write( "Against the current, it takes 2 more hours to travel the same 48 miles.
\n" ); document.write( "what is the speed of my boat in still water?
\n" ); document.write( ":
\n" ); document.write( "Let s = boat speed in still water
\n" ); document.write( "then
\n" ); document.write( "(s+2) = effective speed with the current
\n" ); document.write( "and
\n" ); document.write( "(s-2) = effective speed against the current
\n" ); document.write( ":
\n" ); document.write( "Write a time equation time = distance/speed
\n" ); document.write( ":
\n" ); document.write( "Time downstr + 2 hrs = time upstr
\n" ); document.write( "\"48%2F%28%28s%2B2%29%29\" + 2 = \"48%2F%28%28s-2%29%29\"
\n" ); document.write( ":
\n" ); document.write( "multiply by (s+2)(s-2), results
\n" ); document.write( "48(s-2) + 2(s+2)(s-2) = 48(s+2)
\n" ); document.write( "48s - 96 + 2(s^2-4) = 48s + 96
\n" ); document.write( ":
\n" ); document.write( "Subtract 48s from both sides
\n" ); document.write( "2s^2 - 8 = 96 + 96
\n" ); document.write( "2s^2 = 192 + 8
\n" ); document.write( "2s^2 = 200
\n" ); document.write( "s^2 = \"200%2F2\"
\n" ); document.write( "s^2 = 100
\n" ); document.write( "s = \"sqrt%28100%29\"
\n" ); document.write( "s = 10 mph is speed in still water
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check solution, find the times for each trip
\n" ); document.write( "48/8 = 6 hr
\n" ); document.write( "48/12= 4 hrs
\n" ); document.write( "-------------
\n" ); document.write( "diff: 2 hrs \n" ); document.write( "
\n" );