Решение:
\[ 1,5 = \frac{15}{10} = \frac{3}{2} \]
\[ \frac{3}{2} + \frac{11}{12} = \frac{3 \times 6}{2 \times 6} + \frac{11}{12} = \frac{18}{12} + \frac{11}{12} \]
\[ \frac{18}{12} + \frac{11}{12} = \frac{18 + 11}{12} = \frac{29}{12} \]
\[ \frac{29}{12} = 2 \frac{5}{12} \]
Ответ: 2 5/12