\[\left(\frac{11}{20}+\frac{11}{12}\right)\cdot\frac{9}{4}=\left(\frac{33}{60}+\frac{55}{60}\right)\cdot\frac{9}{4}=\frac{88}{60}\cdot\frac{9}{4}=\frac{22}{15}\cdot\frac{9}{4}=\frac{33}{10}.\]
Ответ: \(\frac{33}{10}\).