If $\overrightarrow{u}, \overrightarrow{v}, \overrightarrow{w}$ are non-coplanar vectors and $p, q$ are real numbers, then the equality $[3\overrightarrow{u} \;\; p\overrightarrow{v} \;\; p\overrightarrow{w}] - [p \overrightarrow{v} \;\; \overrightarrow{w}\; \; q \overrightarrow{u}] - [2 \overrightarrow{w}\; \; q \overrightarrow{v}\;\;q \overrightarrow{u}] = 0$ holds for