GDP is the monetary value of all the goods manufactured and services made within the country for a specific period of time. It shows the economic condition of a country.
As per given data
Total GDP = $12 trillion
Consumption = $8 trillion
Govt. Spending = $2 trillion
Taxes = $0.5 trillion
Disposable income = GDP - Taxes = 12 Trillion - 0.5 trillion = $11.5 trillion