document.write( "Question 799410: Last year Miley Cyrus earned a total of $784 in interest from 2 investments.
\n" ); document.write( "Suppose that she invested a total of $28,000, part of it at 2.4% and the rest at 3.1%.How much did she initially invest at each rate. \n" ); document.write( "
Algebra.Com's Answer #482653 by DrBeeee(684)\"\" \"About 
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Let a = the amount invested at 2.4%
\n" ); document.write( "Let b = the amount invested at 3.1%
\n" ); document.write( "The total amount invested is given by
\n" ); document.write( "(1) a + b = 28,000
\n" ); document.write( "The total interest earned is given by
\n" ); document.write( "(2) 0.024*a + 0.031*b = 784
\n" ); document.write( "Solve (1) for a and substitute it into (2) to get
\n" ); document.write( "(3) 0.024*(28000 - b) + 0.031*b = 784 or
\n" ); document.write( "(4) 672 - 0.024*b + 0.031*b = 784 or
\n" ); document.write( "(5) 0.007*b = 784 - 672 or
\n" ); document.write( "(6) 0.007*b = 112
\n" ); document.write( "(7) b = 112/0.007 or
\n" ); document.write( "(8) b = 16000
\n" ); document.write( "Now use (1) to find a as
\n" ); document.write( "(9) a + 16000 = 28000 or
\n" ); document.write( "(10) a = 28000 - 16000 or
\n" ); document.write( "(11) a = 12000
\n" ); document.write( "Always check your answer. Use (2) to do it.
\n" ); document.write( "Is ( 0.024*12000 + 0.031*16000 = 784)?
\n" ); document.write( "Is (288 + 496 = 784)?
\n" ); document.write( "Is (784 = 784)? Yes
\n" ); document.write( "Answer: Miley Cyrus initially invested $12,000 @ 2.4% and $16,000 @ 3.1%.\r
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