Answer
$\frac{1}{9}$
Work Step by Step
We know that $probability=\frac{\text{number of favorable outcomes}}{\text{number of all outcomes}}$
The events are independent, so we can find the probability of both of them happening by finding the probability of them happening individually and multiplying those.
The probability of the first yellow: $\frac{2}{6}=\frac{1}{3}$, the probability of the second yellow: $\frac{2}{6}=\frac{1}{3}$, thus the probability of both of them happening is: $\frac{1}{3}\frac{1}{3}=\frac{1}{9}$