Find ΔG for CaCO3(s) => CaO(s) + CO2 (g)

Question

Given the following data,

Ca(s) + CO₂(g) + ½ O₂(g) => CaCO₃(s) ΔG^o = -730

2 Ca(s) + O₂(g) => 2 CaO(s) ΔG^o = -1,200

Find ΔG^o for CaCO₃(s) => CaO(s) + CO₂ (g)

I got the 130 as the answer but the correct answer is -130.

Can you explain why it is a negative answer

Answer 1

(1) Ca(s) + CO₂(g) + ½ O₂(g) => CaCO₃(s) ΔG^o = -730

(2) 2 Ca(s) + O₂(g) => 2 CaO(s) ΔG^o = -1,200

reverse (1): CaCO₃(s) ===> Ca(s) + CO₂(g) + 1/2 O₂(g) ∆G = +730 change sign

1/2 (2): Ca(s) + 1/2O₂(g) ==> CaO(s) ∆G = 1/2 x -1200 = -600

I also get positive 130. Not sure how they come up with a negative value.