Answer:
He will earn 18 dollars in interest.
Explanation:
I got this answer form multiplying 10% of 90 by 2, which 10% of 90 is 9, and 9 times 2 is 18, so that's how I got my answer. Please comment on this answer to tell me if it's wrong. I hope it is right and that this really helps you. Have a great day!