Final answer:
The expression (4/9)^-1 evaluates to 9/4 when the negative exponent is simplified. This is done by flipping the fraction, as a negative exponent indicates that the base should be the reciprocal of the value.
Step-by-step explanation:
To evaluate the expression (4/9)-1 without using negative exponents, we recall that a negative exponent indicates that the base should be taken as the reciprocal. So, (4/9)-1 is equivalent to 9/4 because we flip the fraction. Therefore, the correct answer is b) 9/4.