The roots of the quadratic equation $3 x ^ { 2 } - \mathrm { p } x + \mathrm { q } = 0$ are $10 ^ { \text {th} }$ and $11 ^ { \text {th} }$ terms of an arithmetic progression with common difference $\frac { 3 } { 2 }$. If the sum of the first 11 terms of this arithmetic progression is 88, then $q - 2 p$ is equal to