The atomic weight of a metal (M) is 27 and its equivalent weight is 9, the formula of its chloride will be

Assume that formula of the compound is MCl_x.

$$\begin{gathered} \mathrm{Valency}=\frac{\mathrm{Atomic} \mathrm{weight}}{\mathrm{Equivalent} \mathrm{Weight}} \\ \mathrm{Valency}=\frac{27}{9}=3 \end{gathered}$$

Formula of compound becomes MCl₃.