Solve the Following Integer Linear Program

Short Answer

Solve the following integer linear program:

$\begin{array} { l l } \operatorname { MAX } & x _ { 1 } + x _ { 2 } \\\text { subject to: } & 4 x _ { 1 } + 6 x _ { 2 } \leq 22 \\& x _ { 1 } + 5 x _ { 2 } \leq 15 \\& 2 x _ { 1 } + x _ { 2 } \leq 9 \\& x _ { 1 } , x \geq 0 , \text { integer }\end{array}$