Please help me set up these problems. I have been staring at them for hours and I can't tell where I went wrong.

Question

Question: Consider the following reaction: CaCO3(s)→CaO(s)+CO2(g).
Estimate ΔG∘ for this reaction at each of the following temperatures. (Assume that ΔH∘ and ΔS∘ do not change too much within the given temperature range.)
A.) at 320K
B.) at 1100K

Answer 1

If you will type in your work I will find the error.
You should be using
dGrxn = (n*dGf products) - (n*dGf reactants)

Answer 2

@DrBob222 thank you!