For a given chemical reaction
\( \gamma_{1} A + \gamma_{2} B \rightarrow \gamma_{3} C + \gamma_{4} D \)
Concentration of \( C \) changes from \( 10 \, \text{mmol dm}^{-3} \) to \( 20 \, \text{mmol dm}^{-3} \) in \( 10 \, \text{s} \). Rate of appearance of \( D \) is \( 1.5 \) times the rate of disappearance of \( B \) which is twice the rate of disappearance of \( A \). The rate of appearance of \( D \) has been experimentally determined to be \( 9 \, \text{mmol dm}^{-3}\text{s}^{-1} \). Therefore the rate of reaction is __________ \( \text{mmol dm}^{-3}\text{s}^{-1} \). (Nearest Integer)