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| Question 8787:  A man invested $6,000, part of it at 5% simple interest and the rest at 7% simple interest.  If his annual interest income is $372, how much did he invest at each rate?
 Answer by Earlsdon(6294)
      (Show Source): 
You can put this solution on YOUR website! You can set up your equation like this: Let x = the amount invested at 5% simple interest. 5%(x) + 7%($6,000.00-x) = $372.00 Simplify and solve for x. Change percents to decimals.
 0.05(x) + 0.07($6,000.00-x) = $372.00
 0.05x + $420.00 - 0.07x = $372.00 Subtract $420.00 from both sides.
 (0.05-0.07)x = -$48.00
 -0.02x = -$48.00 Divide both sides by -0.02
 x = $2,400.00 invested at 5% simple interest.
 $6,000.00-$2,400.00 = $3,600.00 invested at 7% simple interest.
 Check:
 0.05($2,400.00) + 0.07($3,600) = ?  If it comes to $372.00, all is cool!
 
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