Решить пропорцию: x/12,2=11/13,42.

\[\frac{x}{12,2} = \frac{11}{13,42}\]

\[13,42x = 11 \cdot 12,2\]

\[x = \frac{11 \cdot 12,2}{13,42} = \frac{110 \cdot 122}{1342} =\]

\[= \frac{10 \cdot 122}{122} = 10.\]

\[Ответ:x = 10.\]