Answer: $9602.18
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Work Shown:

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Explanation: I used the compound interest formula. The value of P is the amount loaned to Andy. That amount compounds interest over t = 3 years to arrive at A = 12000 dollars.
The interest rate in decimal form is r = 0.075 and n = 4 is due to quarterly compounding the interest.
The approximate result for P is the most Andy can borrow if he doesn't want A to get larger than $12,000. Smaller values of P will point to values of A such that 0 < A < 12000.