Use the Two-Stage Method to Solve $z=5 x_{1}+4 x_{2}$ Subject To $x_{1}+2 x_{2}=15$

Use the two-stage method to solve.
-Maximize $z=5 x_{1}+4 x_{2}$
Subject to: $x_{1}+2 x_{2}=15$
$\mathrm{x}_{1}+\mathrm{x}_{2} \geq 12$
$2 \mathrm{x}_{1}+\mathrm{x}_{2} \leq 30$
$\mathrm{x}_{1} \geq 0, \mathrm{x}_{2} \geq 0$

A) Maximum is 75 for $x_{1}=15, x_{2}=0$
B) Maximum is 63 for $x_{1}=11, x_{2}=2$
C) Maximum is 57 for $x_{1}=9, x_{2}=3$
D) Maximum is 60 for $x_{1}=0, x_{2}=15$