document.write( "Question 561720: I need help setting up an equation and solving it. Can you please help me?\r
\n" ); document.write( "\n" ); document.write( "Sal has $3200 invested in an account paying 7.2% interest per year. At what rate must he invest an additional $2800 so that the annual interest from the two investments will be $390? \r
\n" ); document.write( "\n" ); document.write( "I have to use the formula p*r*t=I\r
\n" ); document.write( "\n" ); document.write( "Can you please help me set up the equation and help solve it? \n" ); document.write( "
Algebra.Com's Answer #364374 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
Sal has $3200 invested in an account paying 7.2% interest per year.
\n" ); document.write( " At what rate must he invest an additional $2800 so that the annual interest from the two investments will be $390?
\n" ); document.write( ":
\n" ); document.write( "Let r = rate required for the $2800 to get a total $390 return
\n" ); document.write( "I = P*r*t
\n" ); document.write( "where
\n" ); document.write( "p = 2800
\n" ); document.write( "r = interest rate
\n" ); document.write( "t = 1 yr\r
\n" ); document.write( "\n" ); document.write( ":
\n" ); document.write( ".072(3200) + (2800*r*1) = 390
\n" ); document.write( "230.40 + 2800r = 390
\n" ); document.write( "2800r = 390 - 230.40
\n" ); document.write( "2800r = 159.60
\n" ); document.write( "r = \"159.6%2F2800\"
\n" ); document.write( "r = .057 ~ 5.7% is the rate required
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check this
\n" ); document.write( ".072(3200) = 230.40
\n" ); document.write( ".057(2800) = 159.60
\n" ); document.write( "---------------------
\n" ); document.write( "total int: = 390.00
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