document.write( "Question 104705: A motorboat can go 10 miles downstream on a river in 20 min. Its takes 30 min.for this boat to go back upstream the in same 10 miles. Find the speed of the current. \n" ); document.write( "
Algebra.Com's Answer #76239 by ankor@dixie-net.com(22740)\"\" \"About 
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A motorboat can go 10 miles downstream on a river in 20 min. Its takes 30 min.for this boat to go back upstream the in same 10 miles. Find the speed of the current.
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\n" ); document.write( "Let x = speed of boat in still water
\n" ); document.write( "Let y = speed of the current
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\n" ); document.write( "Change minutes to hrs: 20 min = .33 hrs; 30 min = .5 hrs
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\n" ); document.write( "Find the actual speeds, Speed = Dist/time
\n" ); document.write( "Down stream: 10/.33 = 30 mph
\n" ); document.write( "Upstream: 10/.5 = 20 mph
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\n" ); document.write( "Two equations:
\n" ); document.write( "x + y = 30
\n" ); document.write( "x - y = 20
\n" ); document.write( "------------adding eliminates y
\n" ); document.write( "2x + 0y = 50
\n" ); document.write( "x = 50/2
\n" ); document.write( "x = 25 mph is the boat speed in still water.
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\n" ); document.write( "Find the current:
\n" ); document.write( "25 + y = 30
\n" ); document.write( "y = 5 mph is the current \n" ); document.write( "
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