Answer:
10 years
step-by-step explanation:
First, divide 7.5 by 100, you should get 0.075, then multiply 0.075 by 2000, you should get 150, thats how much interest he gains each year, now subtract 2000 from 3500 to see how much he needs to get to 3500, you should get 1500, now divide 1500 by 150, you should get 10, which is how many years he will need to get to 3500 from 2000