\[2\frac{5}{13} \cdot 1\frac{11}{15} + 1\frac{1}{13} \cdot 1\frac{11}{15} =\]
\[= 1\frac{11}{15} \cdot \left( 2\frac{5}{13} + 1\frac{1}{13} \right) =\]
\[= 1\frac{11}{15} \cdot 3\frac{6}{13} = \frac{26 \cdot 45}{15 \cdot 13} = 6\]