SOLUTION: Hanna won $280,000 in the lottery. Hanna wants to invest the money and does so though three savings account one at: 4%,5% and 7%. After the first year Hanna made $15,400 in inte

Question 931523: Hanna won $280,000 in the lottery.
Hanna wants to invest the money and does so though three savings account one at: 4%,5% and 7%. After the first year Hanna made $15,400 in interest.
Hanna invested $20,000 more at 7% than at 5%. How much has Hanna invested in each savings account.
What I have so far
X + Y + Z = 280,000
.04X + .05Y + .07Z = 15,400
????? + ????? + ????? = 0
The last line is where I am stuck. Using rref to brute force the solution hasn't helped. Answer is $80,000 @ 4% $90,000 @ 5% $110,000 @ 7%.
Answer by SucExcProc(1) (Show Source): You can put this solution on YOUR website!
z = y + 20,000
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