document.write( "Question 383989: junior's boat will go 15 miles per hour in still water. if he can go 12 miles downstream in the same amount of time as it takes to go 9 miles upstream, then what is the speed of the current? \n" ); document.write( "

Algebra.Com's Answer #271811 by mananth(16946) $\"\"$ $\"About$

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boat speed in still water = 15 mph
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\n" ); document.write( "let current speed be x mph
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\n" ); document.write( "speed upstream = 15-x mph
\n" ); document.write( "speed downstream = 15+x mph.\r
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\n" ); document.write( "distance downstream = 12 miles
\n" ); document.write( "distance upstream = 9 miles
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\n" ); document.write( "time downstream = time upstream
\n" ); document.write( "..
\n" ); document.write( "t = d/t
\n" ); document.write( " $\"12%2F%2815%2Bx%29=9%2F%2815-x%29\"$
\n" ); document.write( "cross multiply
\n" ); document.write( "12(15-x)=9(15+x)
\n" ); document.write( "180-12x=135+9x
\n" ); document.write( "-9x -9x
\n" ); document.write( "180-12x-9x=135
\n" ); document.write( "-180 -180
\n" ); document.write( "-21x=135-180
\n" ); document.write( "-21x=-45
\n" ); document.write( "/21
\n" ); document.write( "x=-45/-21
\n" ); document.write( "x= 2.14 mph speed of current
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\n" ); document.write( "m.ananth@hotmail.ca \n" ); document.write( "

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