Combination Theorem for Continuous Mappings/Topological Ring/Multiple Rule

Theorem
Let $\struct{S, \tau_S}$ be a topological space.

Let $\struct{R, +, *, \tau_R}$ be a topological ring.

Let $\lambda, \mu \in R$ be arbitrary element in $R$.

Let $f,g : \struct{S, \tau_S} \to \struct{R, \tau_R}$ be continuous mappings.

Then
 * $\lambda * f : \struct{S, \tau} \to \struct{R, \tau_R}$ is continuous.

where $\lambda * f : S \to R$ is the mapping defined by:
 * $\forall x \in S: \map {\paren{\lambda * f}} x = \lambda * \map f x$