Well, if we read this reaction going backwards, if this is the reactant and this is the product that if we subtract a high free energy from a low free energy, we're going to get a positive Delta G. And a positive Delta G means the reaction is endergonic and non spontaneous. And that means it will not take place unless we input a certain amount of energy. And one example of an endorganic reaction that is not spontaneous is the synthesis of ATP molecules inside our body. So to synthesize ATP, we have to actually input energy. And the ATP molecules, when they break down, that is an exergonic reaction and energy is released. And every time we break down ATP molecules inside our body, energy is released.