need help with this!!!

Answer:
$9
Step-by-step explanation
interest = principal * interest rate * length.
so:
answer = (90) * (.1) * (1)
Answer is $9.
Another way of saying it:
You've got $90. You make 10% interest in 1 year if you put it in an account. What do you make? Well, what's 10% of $90? Divide 90 by 10. The answer is $9.
Hope this helps. Let me know if you have questions.