Probability that both are girls =
We have 12/22 chances of choosing a girl on the frist draw......assuming a girl is chosen, then we have 11/21 chances of picking a girl on the second draw....so......
12/22 * 11/21 =
6/11 * 11/21 swap denominators
6/21 * 11 / 11 =
6/21 * 1 =
2 / 7