(Solved): A country's savings \( S \) is defined implicitly in terms of its national income I by the equatio ...

A country's savings \( S \) is defined implicitly in terms of its national income I by the equation \[ S^{2}+\left.\frac{1}{4}\right|^{2}=S \mid+I \] where both \( S \) and I are in billions of dollars. Find the marginal propensity to consume when \( I=12 \) and \( S=8 \). The marginal propensity to consume when \( \mathrm{I}=12 \) and \( \mathrm{S}=8 \) is (Simplify your answer.)