\[- 1,23 \cdot \frac{7}{12} - \frac{7}{12} \cdot 2,37 =\]
\[= - \frac{7}{12} \cdot (1,23 + 2,37) = - \frac{7}{12} \cdot 3,6 =\]
\[= - \frac{7}{12} \cdot \frac{36}{10} = - \frac{7 \cdot 12 \cdot 3}{12 \cdot 10} = - \frac{21}{10} = - 2,1\]