Coupled Reactions Practice Test

A lab group studies two linked reactions that share an intermediate in a closed system. Reaction 1 (spontaneous): $X \rightarrow Y$, $\Delta G = -25\ \text{kJ/mol}$. Reaction 2 (nonspontaneous): $Y \rightarrow Z$, $\Delta G = +30\ \text{kJ/mol}$. The reactions are coupled through intermediate $Y$ so they proceed together as $X \rightarrow Z$. Which statement best describes the thermodynamic favorability of the coupled process?

A student designs a coupled process in which Reaction A (spontaneous) has $\Delta G = -10\ \text{kJ/mol}$ and Reaction B (nonspontaneous) has $\Delta G = +3\ \text{kJ/mol}$. The reactions are coupled through a shared intermediate so they occur together. Which conclusion is most consistent with thermodynamics?