A linear programming model is given as follows: $($ANSWER QUESTION $6-9)$

Minimize $=81+62$

Subject to $41+22>=20$

$61+42<=12$

$1+2>=6$

$1,2>=0$

If the coefficient of $2$ in the objective function decreases to $4,$ what effect will be$?$

If coefficient of x$2$ in objective function changes to $4.$

Then we have Min $=81+42$

The LP model will have multiple solution segment EF with Z$=$

$.$