Given the constraints:
\[3x_1 + 3x_2 \leq 36\]
\[5x_1 + 2x_2 \leq 50\]
\[2x_1 + 6x_2 \leq 60\]
\[x_1 + x_2 = 12\]
Solving the system:
\[3x_1 + 3x_2 = 36\]
\[5x_1 + 2x_2 = 50\]
By substitution:
\[x_1 = \frac{26}{3} \approx 8.66\]
\[x_2 = \frac{10}{3} \approx 3.33\]
Considering the constraint:
\[2x_1 + 6x_2 = 60\]
And the equation:
\[x_1 + x_2 = 12\]
The solution is:
\[x_1 = 3\]
\[x_2 = 9\]
The feasible region satisfying all the given conditions is OABCD.
The coordinates of the corner points are:
\[O(0, 0), A(10, 0), B\left(\frac{26}{3}, \frac{10}{3}\right), C(3, 9), \text{ and } D(0, 10).\]
The maximum value of Z occurs at C(3, 9). Therefore, the optimal solution is:
\[x_1 = 3, x_2 = 9, \text{ and } Z_{\text{max}} = 330.\]