Apply your knowledge about process perspectives on motivation to identify the area of goal$-$setting theory at the root of the problem$\mathrm{.}4.$ A chocolatier visits Singapore and discovers the incredible taste of durian. They decide to create a durian flavored chocolate bar that costs no more than $\backslash (\backslash$$ $4\mathrm{.}50\backslash )$ per pound to produce. If plain chocolate costs $\backslash (\backslash$$ $3\mathrm{.}50\backslash )$ per pound and durian costs $\backslash (\backslash$$ $15\mathrm{.}75\backslash )$ per pound, how many pounds of durian are needed to produce $216$ pounds of durian flavored chocolate bars?