Question $1$: consider the following liner programming

Min z $=5$x$1+7$x$2$

Subject to :

$2$x$1+3$x$2>=42$

$3$x$1+4$x$2>=60$

x$1+$ x$2>=18$

X$1,$x$2>=0$

$$ Solve graphically, using the corner point method.

$$ Determine the optimal mix of the two products?