$6.$ Develop the Branch and bound tree of the following integer programming problem and find out

the optimal solution to the problem by using the Branch and bound method. $(10$ Marks$)$

Max $7$ x$1+9$ x$2$

Subject to

$$ x$1+3$ x$2<=6$

$7$ x$1+$ x$2<=35$

x$1<=7$

x$2<=7$

x$1,$ x$2>=0,$ and are integers.