$5.$Use the branch$-$and$-$bound method $to$ find the optimal solution $to$ the following $LPs$ and then

solve the $LPs$ using MATLAB, show your MATLAB output here $(USE$ THE BRANCH AND BOUND METGOD STEP $BY$ STEP$)$

$at$ the end.

$a.$

maxz$=7x1+3x2$

$s.t.2x1+x29$

$3x1+2x213$

$x1,x20$;${?}_{{?}_{?}}x1,x_{{?}_{?}}2$ integer

$b.$

maxz$=4x1+3x2+x3$

$s.t$; $3x1+2x2+x37$

$2x1+x2+2x311$

$x1,x2,x30$;$x2,x3$ integer