Consider these hypothetical chemical reactions:
A ⇌ B,∆G = 14.3 kJ/mol
B ⇌ C,∆G = -28.4 kJ/mol
C ⇌ D,∆G = 9.10 kJ/mol
what is the free energy, ∆G, for the overall reaction A⇌D?
Express your answer with appropriate units. ∆G = ____.