If you say it's simple interest, then it 7.5% of 6500 added every year instead of 7.5% of the previous year added for the next year, right? So,
Answer: 8 years
7.5/100 x 6500 = 487.5
(10,000 - 6500) / 487.5
= 8 (rounded up to the nearest whole number)
Therefore, it will take 8 years