document.write( "Question 1078008: the boat can travel 35 miles upstream in 7 hours. If boat can go 63 miles downstream in the same a time, how fast is the river current? \n" ); document.write( "
Algebra.Com's Answer #692483 by ankor@dixie-net.com(22740)\"\" \"About 
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the boat can travel 35 miles upstream in 7 hours.
\n" ); document.write( " If boat can go 63 miles downstream in the same a time, how fast is the river current?
\n" ); document.write( ":
\n" ); document.write( "let s = boat speed in still water
\n" ); document.write( "let c = the rate of the current
\n" ); document.write( "from the information given, we can find the effective speed each way
\n" ); document.write( " 35/7 = 5 mph upstream
\n" ); document.write( "and
\n" ); document.write( " 63/7 = 9 mph down stream
\n" ); document.write( "two equations, we can use elimination to find c
\n" ); document.write( "s + c = 9
\n" ); document.write( "s - c = 5
\n" ); document.write( "-------------Subtraction eliminates s
\n" ); document.write( "0 + 2c = 4
\n" ); document.write( "c = 2 mph is speed of the river
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