Algebra.Com's Answer #703402 by ikleyn(52802)![\"\"](\"/images/stars/stars-13.gif\")  
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document.write( "It took an hour for a boat to go six miles upstream. Using the same effort and taking the same path,the boat took only 45 minutes to return.
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document.write( "What was the speed of the boat in still water? What was the speed of the current?
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document.write( "45 minutes =  of an hour.\r\n" );
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document.write( "From the condition you have these two equations\r\n" );
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document.write( " = u - v, (1)\r\n" );
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document.write( " = u + v. (2)\r\n" );
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document.write( "The left side of the equation (1) is the speed of the boat relative the bank of the river when moving with the current, \r\n" );
document.write( "and it is the sum of the rate of the boat in still water and the current rate.\r\n" );
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document.write( "The left side of the equation (2) is the speed of the boat relative the bank of the river when moving against the current, \r\n" );
document.write( "and it is the difference of the rate of the boat in still water and the current rate.\r\n" );
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document.write( "Simplify the equations (1) and (2):\r\n" );
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document.write( "u - v = 6, (3)\r\n" );
document.write( "u + v = 8. (4)\r\n" );
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document.write( "Now add the equations (3) and (4). You will get\r\n" );
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document.write( "2u = 6 + 8 = 14, or u =  = 7.\r\n" );
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document.write( "Thus you just found the speed of the boat in still water. It is 7 miles per hour.\r\n" );
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document.write( "Now it is easy to find the speed of current. It is\r\n" );
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document.write( "v = 8 - u = 8 - 7 = 1 miles per hour.\r\n" );
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document.write( "Check. The boat' speed with the current is 7 + 1 = 8 mph.\r\n" );
document.write( " The time for the down a river trip is  = of an hour.\r\n" );
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document.write( " The boat' speed against the current is 7 - 1 = 6 mph.\r\n" );
document.write( " The time for the trip against the current  = 1 hour.\r\n" );
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document.write( " The solution was checked and found to be correct.\r\n" );
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document.write( "Answer. The speed of the boat in still water is 7 mph. The speed of current is 1 mph.\r\n" );
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document.write( "It is a typical and standard Upstream and Downstream round trip word problem.\r
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document.write( "You can find many similar fully solved sample problems on upstream and downstream round trips with detailed solutions in lessons \r
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document.write( " - Wind and Current problems \r
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document.write( " - More problems on upstream and downstream round trips \r
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document.write( " - Wind and Current problems solvable by quadratic equations \r
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document.write( " - Unpowered raft floating downstream along a river\r
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document.write( " - Selected problems from the archive on the boat floating Upstream and Downstream \r
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document.write( "in this site.\r
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document.write( "Read them attentively and learn how to solve this type of problems once and for all.\r
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document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
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document.write( " - ALGEBRA-I - YOUR ONLINE TEXTBOOK.\r
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document.write( "The referred lessons are the part of this textbook under the section \"Word problems\", the topic \"Travel and Distance problems\".\r
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