The Gini Mean Difference (GMD) is a robust measure of dispersion defined as $G = \frac{1}{n(n-1)} \sum_{i=1}^n \sum_{j=1}^n |x_i - x_j|$. Calculate $G$ for the dataset $X = \{2, 5, 11\}$ and determine the GMD of the transformed dataset $Y = -3X + 10$.