Answer/Step-by-step explanation:
The interest rate is 15% for every 3 years. To find the interest rate subtract the money from the total. Then, divide the total from the difference. Now subtract the quotient from 100 and multiply it by 100 to fin the percentage.
3000 - 450 = 2550
2550 ÷ 3000 = 0.85
100 - 0.85 = 0.15
0.15 x 100 = 15%