document.write( "Question 1099909: Jack inherited 250,000 pesos and invested money in SM, Meralco, and Manila Water. After a year, he got a small return of 16,200 pesos from the three investments. SM returned 6%, Meralco returned 7%, and Manila Water returned 8%. There was 60,000 more invested in Meralco than in Manila Water. How much did he invest in SM, Meralco, and Manila Water? \n" ); document.write( "
Algebra.Com's Answer #714417 by ikleyn(52786)\"\" \"About 
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\n" ); document.write( "Jack inherited 250,000 pesos and invested money in SM, Meralco, and Manila Water. After a year, he got a small return of 16,200 pesos
\n" ); document.write( "from the three investments. SM returned 6%, Meralco returned 7%, and Manila Water returned 8%. There was 60,000 more invested
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document.write( "I will solve the problem by reducing to 2 equations in 2 unknown.\r\n" );
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document.write( "Let S be the amount invested in SM, and\r\n" );
document.write( "let W be the amount invested in Manila Water.\r\n" );
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document.write( "Then investment in Meralco is (W + 60000), according to the condition.\r\n" );
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document.write( "First equation is for the total investment\r\n" );
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document.write( "S + (W + 60000) + W = 250000,    or, equivalently,\r\n" );
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document.write( "S + 2W = 250000 - 60000 = 190000.     (1)\r\n" );
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document.write( "Second equation is for earning\r\n" );
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document.write( "0.06*S + 0.07*(W + 60000) + 0.08*W = 16200.\r\n" );
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document.write( "Multiplying by 100 and simplifying, you can get this form\r\n" );
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document.write( "5*S + 15W = 1620000 - 420000,    or, equivalently,\r\n" );
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document.write( "5S + 15W = 1200000.                     (2)\r\n" );
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document.write( "Now, to make my and your life and calculations easier, I will take off 3 zeroes in the right side of equations (1) and (2). \r\n" );
document.write( "Later I simply will multiply the solution by 1000.\r\n" );
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document.write( "Thus I get these two equations\r\n" );
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document.write( " S +  2W =  190       (3)                 ( instead of (1) )    and\r\n" );
document.write( "6S + 15W = 1200       (4)                 ( instead of (2) )\r\n" );
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document.write( "Now the solution is EASY EXERCISE.   Multiply eq(3) by 6 (both sides) and then subtract from eq(4). You will get\r\n" );
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document.write( "15W - 12W = 1200 - 6*190 = 60,   or\r\n" );
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document.write( "3W = 60  ====>  W = \"60%2F3\" = 20.\r\n" );
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document.write( "Then from (3)  S = 190 - 2W = 190 - 2*20 = 150.\r\n" );
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document.write( "Thus it was invested   20000  in  Manila Water;  \r\n" );
document.write( "                      150000  in  SM;  and\r\n" );
document.write( "                       20000+60000 = 80000 in Meralco.\r\n" );
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document.write( "Check.  20000 + 150000 + 80000 = 250000                (total).     ! Correct !\r\n" );
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document.write( "        0.06*150000 + 0.07*80000 + 0.08*20000 = 16200  (earning)    ! Correct !\r\n" );
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\n" ); document.write( "\n" ); document.write( "Now compare it with the solution by the other tutor.\r
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\n" ); document.write( "\n" ); document.write( "Should I explain more about how the problem SHOULD be solved ?\r
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\n" ); document.write( "\n" ); document.write( "My teachers and all my life taught me to solve problems AS SIMPLE AS POSSIBLE.\r
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\n" ); document.write( "\n" ); document.write( "        (if there are no special reasons to do it by another way).\r
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\n" ); document.write( "\n" ); document.write( "I think that it is really the  ONLY  way   for a homo sapiens.\r
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