Answer: 2000
Explanation:
The following can be gotten from the question:
Principal = Unknown
Rate = 6%
Time = 6 years.
Interest = 720
Note that: Interest = PRT / 100
720 = (P × 6 × 6) / 100
720 = 36P / 100
720 × 100 = 36P
72000 = 36P
Principal = 72000 / 36
Principal = 2000
The amount that he borrowed is 2000.