document.write( "Question 427563: Please help me set up this problem:\r
\n" ); document.write( "\n" ); document.write( "\"Tim paddled his kayak 12 km upstream against a 3 km/hour current and back again in 5 hours and 20 minutes. In that time how far could he have paddled in still water?\" \n" ); document.write( "
Algebra.Com's Answer #297365 by mananth(16946)\"\" \"About 
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\n" ); document.write( " speed in still water = r
\n" ); document.write( "current speed =3
\n" ); document.write( "
\n" ); document.write( "upstream speed = r-3
\n" ); document.write( "downstream speed = r+3
\n" ); document.write( "
\n" ); document.write( "Distance= 12 miles
\n" ); document.write( "
\n" ); document.write( "Time upstream + time downstream = 5.33 hours\r
\n" ); document.write( "\n" ); document.write( "12/(r+3) +12/(r-3 )=5.33
\n" ); document.write( "LCD = (r-3)(r+ 3)
\n" ); document.write( "12*(r-3) +12(r+3 )= 5.33
\n" ); document.write( "12r-36r+12r+36=5.33
\n" ); document.write( "r^2-24r=5.33r^2-47.97
\n" ); document.write( "5.33r^2- 24r-47.97
\n" ); document.write( "Find the roots of the equation by quadratic formula
\n" ); document.write( "a=5.33 b=-24 c=-47.97
\n" ); document.write( "b^2-4ac= 576+1022.72
\n" ); document.write( "b^2-4ac= 1598.72
\n" ); document.write( "\"x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29\"
\n" ); document.write( "\"x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29\"
\n" ); document.write( "x1=(24+ 39.98)/ 10.66
\n" ); document.write( "x1= 6
\n" ); document.write( "x2=(24-39.98) /10.66
\n" ); document.write( "x2= -1.5 ( ignore)
\n" ); document.write( "Speed = 6 mph
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