document.write( "Question 164032: I do not understand how to set this problem up.Please help.Also, how can I check my answer.Thanks in advance.\r
\n" ); document.write( "\n" ); document.write( "Walt made an extra $9000 last year from a part-time job. He invested part of the money at 9% and the rest at 8%. He made a total of $770 in interest. How much was invested at 8%? \n" ); document.write( "
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I do not understand how to set this problem up.Please help.Also, how can I check my answer.Thanks in advance.
\n" ); document.write( "Walt made an extra $9000 last year from a part-time job. He invested part of the money at 9% and the rest at 8%. He made a total of $770 in interest. How much was invested at 8%?
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\n" ); document.write( "He invested some at 9%, call that N dollars. The rest at 8%, call the E dollars.\r
\n" ); document.write( "\n" ); document.write( "N + E = 9000
\n" ); document.write( "N*.09 + E*.08 = 770
\n" ); document.write( "From eqn 1, E = 9000-N
\n" ); document.write( "Substitute that into eqn 2
\n" ); document.write( "N*.09 + (9000-N)*.08 = 770
\n" ); document.write( ".09N + 720 - .08N = 770
\n" ); document.write( ".01N = 50
\n" ); document.write( "N = 5000
\n" ); document.write( "E is 5000-N, or $4000
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\n" ); document.write( "To check:
\n" ); document.write( "5000*.09 + 4000*.08 ?? 770
\n" ); document.write( "450 + 320 = 770, so it's correct.\r
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