What would be the size of Investment (I) as per National Income Accounting Identity in an open economy,…

From the open-economy national income accounting identity $Y = C + I + G + NX$ and disposable income $Y - T = C + S$, subtracting yields the sectoral balances identity $S - I = (G - T) + NX = \text{BD} + \text{NX}$. Substituting private savings $S = 1{,}000$, budget deficit $\text{BD} = 150$, and net exports $\text{NX} = -100$ gives $1{,}000 - I = 150 + (-100) = 50$, so $I = 1{,}000 - 50 = 950$.