Private saving is $5 trillion, calculated as disposable income (Y-T) of $9 trillion minus consumption (C) of $8 trillion. Public saving is -$1 trillion, calculated as total revenue (TR) of $2 trillion minus total expenditure (T) of $3 trillion. Private saving plus public saving equals investment (I) of $4 trillion, demonstrating that in a closed economy, total saving must equal total investment.