What is the r-value of a wall section made of 2x4's, 1/2 drywall, 1/2 OSB, and 3 1/2 fiberglass insulation?

This is for a construction materials classI need to compair the r-factor of this wall to the r-factor of a 3 1/2quot; ridgid foam insulation wall.

3 1/2 fiberglass insulation has an R value of 11, not 13.

Al has a positive (+) charge because it has more protons than electrons