$($a$)$ Determine whether this LP is a maximization or minimization problem, and whether the constraintis a $""$ or a $""$ constraint. Explain your reasons.

$($b$)$ Now replace $"RHS"$ by "objective coefficient" and interpret this graph depicting how the optimal objective changes as the objective coefficient of a primal variable is changed. Determine if the linear program is a maximization or minimization problem, and whether the $($optimal$)$ value of the primal variable is nonnegative or nonpositive.