how to solve it

Question

You invested $20,000 in two accounts. One account pays an annual interest rate of 6% and the second account pays an annual interest rate of 7.5%. How much did you invest in each account if the total interest earned for the year was $1440?

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Answer 1

If $x you invest on first account and $y on second then we have system of equations:

x + y = 20000

0.06x + 0.075y = 1440

From first equation y = 20000 - x,

and put in second equation: 0.06x + 0.075(20000 - x) = 1440, 0.06x + 1500 - 0.075x = 1440, -0.015x = - 60;

From here x = $4000 and y = $16000