document.write( "Question 752609: A boat covers 30km upstream and 22 km downstrean in 8 hours. Also,it takes 4 more hours to travel 40 km upstream and 44 km downstrean. Find the speed of the boat in still water and that of the stream. \n" ); document.write( "
Algebra.Com's Answer #457889 by dkppathak(439)\"\" \"About 
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let speed of boat in still water is x km /h
\n" ); document.write( "and speed of current of water is y km/h
\n" ); document.write( " speed up stream =x-y km/h
\n" ); document.write( " speed of down stream =x+y km/h
\n" ); document.write( "speed =distance / time
\n" ); document.write( "or
\n" ); document.write( "time =distance/ speed
\n" ); document.write( "t1=30/x-y
\n" ); document.write( "t2 =22/x+y
\n" ); document.write( "as per given conditions
\n" ); document.write( "t1 +t2 =8
\n" ); document.write( "30/x-y +22/x+y =8 (i)
\n" ); document.write( "similarly
\n" ); document.write( "40/x-y +44/x+y =12 (ii)
\n" ); document.write( "let x-y =u
\n" ); document.write( "x+y =v
\n" ); document.write( "we can rewrite equation as
\n" ); document.write( "30/u +22/v = 8 (iii)
\n" ); document.write( "40/u +44/v = 12 (iv)
\n" ); document.write( "by solving equations by elimination method
\n" ); document.write( "we can solve U =5
\n" ); document.write( "and V=11
\n" ); document.write( "by substitute the value of u and v
\n" ); document.write( "we can rewrite equations as
\n" ); document.write( "x-y =5
\n" ); document.write( "x +y =11
\n" ); document.write( "by solving these equations
\n" ); document.write( "we can get
\n" ); document.write( "x=8 km/h
\n" ); document.write( "y=3 km/h\r
\n" ); document.write( "\n" ); document.write( "ANSWER speed of boat in still water is 8km/h
\n" ); document.write( "and speed of current of water is 3 km/h \r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
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