ACT Practice Question: Exponent terms being subtracted

 
Here is a practice question on subtracting exponent expressions, remember that there are no general rules for adding and subtracting exponent terms.

$\dfrac{1}{3^{30}} – \dfrac{2}{3^{31}}$ is equal to

1. $\quad \dfrac{2}{3^{61}}$
2. $\quad \dfrac{1}{3^{31}}$
3. $\quad \dfrac{1}{3^{30}}$
4. $\quad \dfrac{2}{3^{30}}$
5. $\quad \dfrac{1}{3}$