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You can put this solution on YOUR website!
A boat travelled 336 miles downstream and back.
\n" ); document.write( " The trip downstream took 12 hours. The trip back took 14 hours.
\n" ); document.write( " What is the speed of the boat in still water?
\n" ); document.write( " What is the speed of the current?
\n" ); document.write( ":
\n" ); document.write( "let s = boat speed in still water
\n" ); document.write( "let c = rate of the current
\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( "12(s+c) = 336
\n" ); document.write( "14(s-c) = 336
\n" ); document.write( "we are in luck; we can greatly simplify both these equations
\n" ); document.write( "divide the first by 12, divide the 2nd by 14, and you have
\n" ); document.write( "s + c = 28
\n" ); document.write( "s - c = 24
\n" ); document.write( "--------------Addition eliminates c, find s
\n" ); document.write( "2s + 0 = 52
\n" ); document.write( "s = 52/2
\n" ); document.write( "s = 26 mph in still water
\n" ); document.write( "and
\n" ); document.write( "26 + c = 28
\n" ); document.write( "c = 28 - 26
\n" ); document.write( "c = 2 mph is the rate of the current
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check this using the 1st original equation
\n" ); document.write( "12(26 + 2) = 336
\n" ); document.write( "12(28) = 336
\n" ); document.write( "You can check this for yourself in the 2nd original equation \n" ); document.write( "