xij,zimins.t. i∑cij∑xij⎩⎨⎧∑iaijxij≥1∑jxij≤zi∑izi≤6xij≥0zi∈{0,1}∀j∈gym∀i∈inventory∀i,j∀i \begin{aligned}\min_{x_{ij},z_{i}} & \sum_{i}c_{i}\sum_{j}x_{ij}\\
\text{s.t. } & \begin{cases}
\sum_{i}a_{ij}x_{ij}\ge1 & \forall j\in\text{gym}\\
\sum_{j}x_{ij}\le z_{i} & \forall i\in\text{inventory}\\
\sum_{i}z_{i}\le6\\
x_{ij}\ge0 & \forall i,j\\
z_{i}\in\left\{ 0,1\right\} & \forall i
\end{cases}
\end{aligned}