Question 928730:  I don't understand where the 3x comes from in this equation:. 
12x + .07(25000 - 3x) + .06(2x) = 1945 
.12x - (.21x) + .12x = 1945 - 1750 
.03x= 195 
x = $6500, amount at 12% 
2x = $13,000, amount at 6% 
25000-3%2A6500%29 = $5,500, amount at 7% 
And..checking 
Sum = $25,000
 
Original problem: Bradley has $25,000 that he wants to invest. He invests it in accounts paying 12%, 7%, and 6% simple interest. The account paying 12% is higher-risk account, so he wants the amount in that account to be half of the amount he has in the account paying 6% simple interest. If his annual interest is $1945, how much is invested at each rate? 
 Answer by ewatrrr(24785)      (Show Source): 
You can  put this solution on YOUR website! 12x + .07(25000 - 3x) + .06(2x) = 1945 
 .12x - (.21x) + .12x = 1945 - 1750 
  
 .03x= 195 
 x = $6500, amount at 12% 
 2x = $13,000, amount at 6% 
 25000-3%2A6500%29 = $5,500, amount at 7% 
 And..checking 
 Sum = $25,000  
 Original problem: 
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