Find 4 divided by $\frac{4}{9}$.
I want to find 4 divided by a fraction, which is the same as multiplying 4 by the reciprocal of the fraction. The reciprocal of $\frac{4}{9}$ is $\frac{9}{4}$, so I can write the problem as 4 times $\frac{9}{4}$. I can simplify this by canceling out the common factor of 4 in the numerator and denominator, leaving me with 1 times 9. 1 times 9 is just 9, so the answer is 9. 