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| Question 633377:  Melissa invested a sum of money at 3% annual interest. She invested three times that sum at 5% annual interest. If her total yearly interest from both investments was 5400, how much was invested at 3%
 Answer by John10(297)
      (Show Source): 
You can put this solution on YOUR website! Melissa invested a sum of money at 3% annual interest. She invested three times that sum at 5% annual interest. If her total yearly interest from both investments was 5400, how much was invested at 3% ? 
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 Hello, we need to find the sum of money which invest at 3% interest.
 So we will assume that amount is x. Thus the amount of money invest into 5% is 3x.
 We know that the sum of interest from both account (3% and 5%) is 5400.
 We will have an equation:
 0.03x + 0.05(3x) = 5400
 0.03x + 0.15x = 5400
 0.18x = 5400
 x = 5400/0.18
 x = 30,000
 Thus the sum of money invest in 3% is $30,000.
 Hope it helps:)
 John10
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