Calculate the enthalpy of formation of 1 mole SO₂(g) from the standard enthalpy changes of the following reactions:

2SO₃​(g) → 2SO₂(g) + O₂
ΔH°rxn 1 = +196 kJ

2S(s)+3O₂​(g) → 2SO₃​(g)

ΔH°rxn 2 = -790 kJ

S(s)+O₂ → SO₂(g)

ΔH°rxn 3 =?