I believe the most appropriate equations are 1 and 3; that is ATP + H2O = ADP + Pi ΔGI =- 7 kcal/mol and Glucose + Pi = Glucose-6-phosphate +H2O ΔG3 = +3.3 kcal/mol Reaction coupling is a strategy used by cells in which an energetically favorable reaction such as hydrolysis of ATP is directly linked with an energetically unfavorable reaction.