Solve each of the following system of equations in R. 18.

$0<\frac{-x}{2}<3$

$\Rightarrow 0<-x<6 \quad$ (Multiplying throughout by 2 )

$\Rightarrow 0>x>-6 \quad$ (Multiplying throughout by $-1$ )

$\Rightarrow x \in(-6,0)$

Hence, the interval $(-6,0)$ is the solution of the given set of inequations.