Решение:
$${\frac{11}{5}} + {\frac{13}{4}} = {\frac{11 \cdot 4}{5 \cdot 4}} + {\frac{13 \cdot 5}{4 \cdot 5}} = {\frac{44}{20}} + {\frac{65}{20}} = {\frac{44 + 65}{20}} = {\frac{109}{20}} = 5,45$$
Ответ: 5,45