document.write( "Question 1013960: A boat traveled 210 miles downstream and back. The trip dwonstream took 10hours. The trip back took 70 hours. What is the speed of the boat in still water? What is the speed of the current? Explain. \n" ); document.write( "
Algebra.Com's Answer #630266 by ankor@dixie-net.com(22740)\"\" \"About 
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let s = the boat speed in still water
\n" ); document.write( "let c = speed of the current
\n" ); document.write( "then
\n" ); document.write( "(s+c) = effective speed down stream
\n" ); document.write( "and
\n" ); document.write( "(s-c) = effective speed upstream
\n" ); document.write( ":
\n" ); document.write( "A boat traveled 210 miles downstream and back.
\n" ); document.write( " The trip dwonstream took 10hours.
\n" ); document.write( " The trip back took 70 hours.
\n" ); document.write( " What is the speed of the boat in still water?
\n" ); document.write( " What is the speed of the current? Explain.
\n" ); document.write( ":
\n" ); document.write( "Write a distance equation for each way. dist = time * speed
\n" ); document.write( "10(s+c) = 210
\n" ); document.write( "70(s-c) = 210
\n" ); document.write( "simplify both equation, divide the 1st by 10, the 2nd by 70
\n" ); document.write( "s + c = 21
\n" ); document.write( "s - c = 3
\n" ); document.write( "---------------addition eliminates c, find s
\n" ); document.write( "2s + 0 = 24
\n" ); document.write( "s = 24/2
\n" ); document.write( "s = 12 mph in still water
\n" ); document.write( "Find c
\n" ); document.write( "12 + c = 21
\n" ); document.write( "c = 21 - 12
\n" ); document.write( "c = 9 mph is the speed of the current
\n" ); document.write( ";
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check solutions in the 2nd original equation
\n" ); document.write( "70(12 - 9) = 210
\n" ); document.write( "70(3) = 210 mi \n" ); document.write( "
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