document.write( "Question 309614: Mary (m) is 4 years older than Rico (r). Ten years ago Mary was 3 times as old as Rico was then. a) how old are they now? b) determine if answer is correct by checking that it satisfies the conditions of the problem\r
\n" ); document.write( "\n" ); document.write( "m + 4 = r \r
\n" ); document.write( "\n" ); document.write( "r(3) = m -10 ???\r
\n" ); document.write( "\n" ); document.write( "I don't know how to set the equation up or figure an age if I don't have any ages to begin with.
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Algebra.Com's Answer #221441 by Edwin McCravy(20056) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "You are interpreting the sentences incorrectly.\r\n" );
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\n" ); document.write( "Mary (m) is 4 years older than Rico (r).
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document.write( "Think this way.  \r\n" );
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document.write( "A.  Mary is older than Rico\r\n" );
document.write( "B.  Therefore m is greater than r and r is smaller than m\r\n" );
document.write( "C.  Therefore you must add 4 to the smaller (r) in order for it\r\n" );
document.write( "    to equal the larger (m).\r\n" );
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document.write( "Do you see that you have this exactly backward with your \r\n" );
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m + 4 = r
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document.write( "You added to the larger m, making it even larger, and then put that\r\n" );
document.write( "equal to the smaller.  Do you now see why that is incorrect?  \r\n" );
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document.write( "You should have \r\n" );
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document.write( "SMALLER + 4 = LARGER or\r\n" );
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document.write( "      r + 4 = m\r\n" );
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document.write( "Then for the second part\r\n" );
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\n" ); document.write( "Ten years ago Mary was 3 times as old as Rico was then
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document.write( "Think this way:\r\n" );
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document.write( "A.  Ten years ago Mary was m-10 \r\n" );
document.write( "B.  Ten years ago Rico was r-10\r\n" );
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document.write( "Therefore \r\n" );
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document.write( "C.  m-10 WAS 3 times r-10\r\n" );
document.write( "D.  The equation is m-10 = 3(r-10)\r\n" );
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document.write( "Do you see that your equation \"r(3) = m -10\" is wrong because you\r\n" );
document.write( "multiplied Rico's PRESENT age by 3 when you should have instead\r\n" );
document.write( "multiplied his age TEN YEARS AGO by 3.\r\n" );
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document.write( "So the correct system of two equations in two unknowns m and r is\r\n" );
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document.write( "Do you know how to solve that system of eauations?  If not\r\n" );
document.write( "post again asking how to solve that system.\r\n" );
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document.write( "Answer: m = 16, r = 12\r\n" );
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document.write( " b) determine if answer is correct by checking that it satisfies the conditions of the problem \r\n" );
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document.write( "Mary is 16, which makes her 4 years older than Rico, who is 12. Ten years ago\r\n" );
document.write( "Mary was 16-10 or 6, and Rico was 12-10 or 2, and 6 is indeed 3 times 2, which\r\n" );
document.write( "is how old Rico was then.\r\n" );
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document.write( "So it checks.\r\n" );
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document.write( "Edwin
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