document.write( "Question 1035246: My brother is 3 years elder to me. My father was 28 years of age when my sister was born while my mother was 26 years of age when I was born.if my sister was was 4 years of age when my brother was born, what was the age of my father when my brother was born? \n" ); document.write( "

Algebra.Com's Answer #649900 by ikleyn(52787) $\"\"$ $\"About$

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\n" ); document.write( "My brother is 3 years elder to me. My father was 28 years of age when my sister was born
\n" ); document.write( "while my mother was 26 years of age when I was born.if my sister was was 4 years of age when my brother was born,
\n" ); document.write( "what was the age of my father when my brother was born?
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document.write( "Let   i = my age now,\r\n" );
document.write( "      b = my brother's age now,\r\n" );
document.write( "      s = my sister's age now,\r\n" );
document.write( "      f = my father's age now, and\r\n" );
document.write( "      m = my mother's age now.\r\n" );
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document.write( "Now I will algebreze the condition, by writing the equation/expression for each statement of the problem.\r\n" );
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document.write( "1. \"My brother is 3 years elder to me.\"                      ---> b = i + 3      (1)\r\n" );
document.write( "2. \"My father was 28 years of age when my sister was born\"   ---> f = s + 28     (2)\r\n" );
document.write( "3. \"my mother was 26 years of age when I was born\"           ---> m = i + 26     (3)\r\n" );
document.write( "4. \"my sister was 4 years of age when my brother was born\"   ---> s = b + 4.     (4)\r\n" );
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document.write( "We have 5 unknowns and only 4 equations. But still keep the positive attitude.\r\n" );
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document.write( "What do they want? - They want from us to find  f-b.   OK.\r\n" );
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document.write( "f - b = (s+28) - (s-4).   (5)   <--- I replaced f by (s+28) based on (2), and replaced b by (s-4) based on (4).\r\n" );
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document.write( "So, I can continue (5) in this way:\r\n" );
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document.write( "f - b = s + 28 - s + 4 = 32.\r\n" );
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document.write( "It is just the answer to the problem's question:\r\n" );
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document.write( "   \"what was the age of my father when my brother was born?\" - The father's age was 32 years at that time.\r\n" );
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document.write( "The problem is solved.\r\n" );
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document.write( "Probably, there is a shorter way to solve the problem.\r\n" );
document.write( "But developing this solution, you learned so many things, that our efforts are justified.\r\n" );
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document.write( "It seems to me that a young reader may have a question: \r\n" );
document.write( "   how it could happen that we were able to solve the system of 4 equations in 5 unknowns?\r\n" );
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document.write( "The answer is: we didn't solve the system.\r\n" );
document.write( "We only found the value of some expression (\"f - b\" in this case) of the variables, based on given equations.\r\n" );
document.write( "But we didn't solve the entire system.\r\n" );
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document.write( "Also, you may see that we used only some part of the given data, and didn't use all of them. \r\n" );
document.write( "It is also the trick of the authors of the problem: They included a non-necessary information to miss the readers. \r\n" );
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document.write( "But, happily, we were not missed.\r\n" );
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document.write( "In whole, this is brilliant/outstanding problem.\r\n" );
document.write( "Thanks to its authors and to the sender for posting it.\r\n" );
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