Algebra.Com's Answer #714245 by ikleyn(52788)![\"\"](\"/images/stars/stars-13.gif\")  
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document.write( "The speed downstream is  = 24 km/h.\r\n" );
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document.write( "It is equal to the sum of the boat speed at still water (U) and the current speed (v):\r\n" );
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document.write( "u + v = 24. (1)\r\n" );
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document.write( "The speed downstream is  = 20 km/h.\r\n" );
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document.write( "It is equal to the DIFFERENCE of the boat speed at still water (U) and the current speed (v):\r\n" );
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document.write( "u - v = 20. (2)\r\n" );
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document.write( "Thus you have these two equations for 2 unknowns:\r\n" );
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document.write( "u + v = 24, (1)\r\n" );
document.write( "u - v = 20. (2)\r\n" );
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document.write( "Add the equations. You will get\r\n" );
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document.write( "2u = 24 + 18 = 44 ====> u =  = 22.\r\n" );
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document.write( "Thus you just found the speed of the the boat in still water. It is 22 km/h.\r\n" );
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document.write( "Then from (1) v = 24-u = 24 - 22 = 2 km/h.\r\n" );
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document.write( "Answer. The speed of the the boat in still water is 22 km/h.\r\n" );
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document.write( " The speed of the current is 2 km/h.\r\n" );
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document.write( "Solved.\r
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document.write( "To see other similar solved problems, look into the 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( " - Selected problems from the archive on a plane flying with and against the wind \r
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document.write( "in this site.\r
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