document.write( "Question 828710: A boat can travel 16 mph in still water. It can make the trip upstream to a marina in 20 minutes and can return to its starting point in 15 minutes. What is the speed of the current ? \n" ); document.write( "
Algebra.Com's Answer #499462 by TimothyLamb(4379)\"\" \"About 
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\n" ); document.write( "s = d/t
\n" ); document.write( "d = s*t
\n" ); document.write( "---
\n" ); document.write( "up:
\n" ); document.write( "d = (16 - x)20/60
\n" ); document.write( "---
\n" ); document.write( "down:
\n" ); document.write( "d = (16 + x)15/60
\n" ); document.write( "---
\n" ); document.write( "(16 - x)1/3 = (16 + x)1/4
\n" ); document.write( "(16 - x)4 = (16 + x)3
\n" ); document.write( "64 - 4x = 48 + 3x
\n" ); document.write( "7x = 16
\n" ); document.write( "x = 16/7
\n" ); document.write( "---
\n" ); document.write( "speed of current: 2.3 mph
\n" ); document.write( "---
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