$$\left | 18ab-27a \right |+(2b-3)=\left | 18 \cdot (-\frac{1}{9}) \cdot 1.2-27 \cdot (-\frac{1}{9}) \right |+(2 \cdot 1.2-3)=\left | -2 \cdot 1.2+3 \right |+2.4-3=\left | -2.4+3 \right |-0.6=0.6-0.6=0$$
Ответ: $$0$$.