\begin{aligned} &\text { b) Maximise } 2 x_{1}+3 x_{2}+2 x_{3} \text { subject to }\\ &3 x_{1}+x_{2}+2 x_{3} \leq 6\\ &x_{1}+x_{2}+x_{3} \leq 4\\ &2 x_{1}+6 x_{2}+6 x_{3} \leq 20\\ &x_{1},

x_{2}, x_{3} \geq 0 \end{aligned}