A$)$ Determine the new optimal objective function value when the following changes happen. All questions are independent.

A$\mathrm{.}1)$ Available leather is increased to $70f{t}^2.$

A$\mathrm{.}2)$ Available leather is decreased by $1f{t}^2.$

A$\mathrm{.}3)$ Available sewing hours are changed to $86$ hours.

A$\mathrm{.}4)$ Available sewing hours are changed to $60$ hours.

A$\mathrm{.}5)$ Available leather is changed to $67f{t}^2,$ and available finishing hours are changed to $70$ hours.

A$\mathrm{.}6)$ Would you recommend hiring an additional part$-$time finishing worker at $$15$ an hour for $2$ hours a day?