Needing help with this cell biology question. Thanks!

The values for G in cells have been determined for five reactions in a metabolic pathway. What do these values tell you about the rate of each of these reactions? If the G for the third step in the series G + H J + K is +4.5kcal/mole, what is the G for the reverse reaction? What two distinct methods might account for the ability of the third step to proceed in a cell?