document.write( "Question 335675: Hello!\r
\n" ); document.write( "\n" ); document.write( "A boat goes 630 miles downstream in the same time it can go 540 miles upstream. The speed of the current is 3 miles per hour. Find the speed of the boat in still water.\r
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Algebra.Com's Answer #240822 by Fombitz(32388)\"\" \"About 
You can put this solution on YOUR website!
Rate*Time=Distance
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\n" ); document.write( "\n" ); document.write( "Let the speed of the boat be B.
\n" ); document.write( "Downstream,
\n" ); document.write( "1.\"%28B%2B3%29t=630\"
\n" ); document.write( "Upstream,
\n" ); document.write( "2.\"%28B-3%29t=540\"
\n" ); document.write( "From eq. 1,
\n" ); document.write( "\"t=630%2F%28B%2B3%29\"
\n" ); document.write( "Substitute into eq. 2,
\n" ); document.write( "\"%28B-3%29%28630%2F%28B%2B3%29%29=540\"
\n" ); document.write( "\"630%28B-3%29=540%28B%2B3%29\"
\n" ); document.write( "\"630B-1890=540B%2B1620\"
\n" ); document.write( "\"90B=3510\"
\n" ); document.write( "\"highlight%28B=39%29\" mph
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