document.write( "Question 1103961: The number of persons entering a building at 10:00 a.m one day was 235 more than that of 10:00 a.m the previous day. The total for both days was 885. how many persons entered the building at 10:00 a.m on each day? \n" ); document.write( "

Algebra.Com's Answer #718669 by ikleyn(52884) $\"\"$ $\"About$

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document.write( "The condition is equivalent to this system of 2 equations in 2 unknowns:\r\n" );
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document.write( "x - y = 235,    (1)\r\n" );
document.write( "x + y = 885.    (2)\r\n" );
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document.write( "You can solve it in 2 (two, TWO) ways.\r\n" );
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document.write( "1.  Elimination method\r\n" );
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document.write( "    Add the two equations. Then the terms \"y\" will cancel each other, and you will get very simple equation for one single unknown x only:\r\n" );
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document.write( "    2x = 235 + 885  ====>  2x = 1120  ====>  x =  = 560.\r\n" );
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document.write( "    Then from eq(2)  y = 885 - x = 885 - 560 = 325.\r\n" );
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document.write( "Answer.  560 people in the second day and 325 people in the first day.\r\n" );
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document.write( "2.  Substitution method\r\n" );
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document.write( "    From eq(1) express  x = 235 + y and substitute it into the second equation. You will get\r\n" );
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document.write( "    (235+y) + y = 885,\r\n" );
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document.write( "     235 + 2y = 885  ====>  2y = 885 - 235 = 650  ====>  y =  = 325,\r\n" );
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document.write( "     and you obtain the same answer in this way, of course.\r\n" );
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