document.write( "Question 975138: Here is my question:\r
\n" ); document.write( "\n" ); document.write( "A boat travels 12km upstream and back in 3 hours. If the speed of the current is 3 km/h throughout, make an equation and find the speed of the boat in still water.\r
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Algebra.Com's Answer #597066 by MathTherapy(10810)\"\" \"About 
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\n" ); document.write( "Here is my question:\r
\n" ); document.write( "\n" ); document.write( "A boat travels 12km upstream and back in 3 hours. If the speed of the current is 3 km/h throughout, make an equation and find the speed of the boat in still water.\r
\n" ); document.write( "\n" ); document.write( "Thank you very much!
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Let speed of boat in still water, be S
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document.write( "Time taken to travel upstream: \"12%2F%28S+-+3%29\"
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document.write( "Time taken to travel downstream: \"12%2F%28S+%2B+3%29\"
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document.write( "Therefore, we have: \"12%2F%28S+-+3%29+%2B+12%2F%28S+%2B+3%29+=+3\"
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document.write( "12(S + 3) + 12(S – 3) = 3(S – 3)(S + 3) ----- Multiplying by LCD, (S – 3)(S + 3)
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document.write( "\"12S+%2B+36+%2B+12S+-+36+=+3%28S%5E2+-+9%29\"
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document.write( "\"12S+%2B+12S+%2B+36+-+36+=+3S%5E2+-+27\"
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document.write( "\"24S+=+3S%5E2+-+27\"
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document.write( "\"3S%5E2+-+24S+-+27+=+0\"
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document.write( "\"3%28S%5E2+-+8S+-+9%29+=+3%280%29\"
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document.write( "\"S%5E2+-+8S+-+9+=+0\"
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document.write( "(S - 9)(S + 1) = 0 
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document.write( "S, or speed in still water = \"highlight_green%289%29\" mph	     OR	        S = - 1 (ignore) \n" );
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