Question

In a four-sector open economy, circular flow equilibrium requires that total leakages ($S + T + M$) equal total injections ($I + G + X$). If domestic investment ($I$) increases by $\$40\text{ billion}$, government spending ($G$) decreases by $\$15\text{ billion}$, exports ($X$) rise by $\$25\text{ billion}$, tax revenues ($T$) increase by $\$20\text{ billion}$, and imports ($M$) remain constant, what change in household savings ($S$) is required to maintain equilibrium?