Let $R$ be a commutative ring. Show that $(R$-$Mod, \otimes ,R)$ is a symmetric monoidal category.
Furthermore, show that it is a closed symmetric monoidal category.
I've seen statements of these facts, but can't seem to find the proofs anywhere.
Here is the definition of a symmertric monoidal category https://ncatlab.org/nlab/show/symmetric+monoidal+category