document.write( "Question 168004: Roberto invested some money at 7%, and then invested $3000 more than twice this amount at 10%. His total annual income from the two investments was $3810. How much was invested at 10%?\r
\n" ); document.write( "\n" ); document.write( "P.S. I am assuming that this is to be translated into an actual formula in order to obtain the answer, but I can get really frustrated with almost all word problems. Please help me. Thank you. \n" ); document.write( "

Algebra.Com's Answer #123859 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Once you call the unknown by a letter, it falls into place, usually
\n" ); document.write( "Let $\"x\"$ = the amount invested at 7%
\n" ); document.write( "Then it gives you
\n" ); document.write( " $\"2x+%2B+3000\"$ = the amount invested at 10%
\n" ); document.write( "Now the problem wants to know how much was made from the 2 investments
\n" ); document.write( "Think of this as the profit.
\n" ); document.write( " $\".7x+%2B+.1%2A%282x+%2B+3000%29+=+3810\"$
\n" ); document.write( " $\".7x+%2B+.2x+%2B+300+=+3810\"$
\n" ); document.write( " $\".9x+=+3810+-+300\"$
\n" ); document.write( " $\".9x+=+3510\"$
\n" ); document.write( " $\"x+=+3900\"$
\n" ); document.write( "This was the amount invested @ 7%
\n" ); document.write( " $\"2%2A3900+%2B+3000+=+10800\"$
\n" ); document.write( "This was the amount invested @ 10%
\n" ); document.write( "check:
\n" ); document.write( " $\".7x+%2B+.1%2A%282x+%2B+3000%29+=+3810\"$
\n" ); document.write( " $\".7%2A3900+%2B+.1%2A10800+=+3810\"$
\n" ); document.write( " $\"2730+%2B+1080+=+3810\"$
\n" ); document.write( " $\"3810+=+3810\"$
\n" ); document.write( "OK
\n" ); document.write( "He invested $10,800 @ 10%
\n" ); document.write( " \n" ); document.write( "

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