Solve the Standard Minimization Problem Using Duality $c = 3 s + 3 t + 3 u$

Short Answer

Solve the standard minimization problem using duality.
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Minimize $c = 3 s + 3 t + 3 u$ ​
subject to $$\begin{array} { l } 3 s + 2 t + u \geq 60 \\2 s + t + 3 u \geq 60 \\s + 3 t + 2 u \geq 60 \\s \geq 0 , t \geq 0 , u \geq 0\end{array}$$ ​ $$c = \quad s = \quad t = \quad u =$$