28. Define a new operation “ $\oplus$ ” : $a \oplus b=\left\{\begin{array}{ll}a, & (\text { if } a \geq b) \\ b, & \text { (if } a<b)\end{array}\right.$, for example: $6.5 \oplus 2=6.5,1 \oplus 7=7$. Then $\frac{2.3 \oplus \frac{7}{3}+\frac{1}{9} \oplus 0.1}{\frac{4}{9} \oplus 0.8} \div 11=$ $\qquad$
Answer: $\frac{5}{18}$