\[ A_1 = 4 \times 12 = 48, \quad A_2 = 6 \times 8 = 48. \]
For part 1: \[ \bar{x}_1 = 0, \quad \bar{y}_1 = 8 + \frac{4}{2} = 10. \] For part 2: \[ \bar{x}_2 = 0, \quad \bar{y}_2 = \frac{8}{2} = 4. \]
\[ A = A_1 + A_2 = 48 + 48 = 96. \]
\[ \bar{x} = 0, \quad \bar{y} = \frac{A_1 \bar{y}_1 + A_2 \bar{y}_2}{A} = \frac{48(10) + 48(4)}{96} = 7. \]