A person invested ​$7200 for 1​ year, part at 8​%, part at 9​%, and the remainder at 14​%.

Question

A person invested ​$7200 for 1​ year, part at 8​%, part at 9​%, and the remainder at 14​%. The total annual income from these investments was $831. The amount of money invested at 14​% was ​$600 more than the amounts invested at 8​% and 9​% combined. Find the amount invested at each rate.