Cho 0,(21) : 2,4 = x + 0,(12)

A

- Hướng dẫn giải

\(\begin{array}{l}0,(21):2,4 = x + 0,(12)\\ \Leftrightarrow \frac{{21}}{{99}}:2,4 = x + \frac{{12}}{{99}}\\ \Leftrightarrow x + \frac{4}{{33}} = \frac{{35}}{{396}}\\ \Leftrightarrow x = - \frac{{13}}{{396}}\end{array}\)