A country’s GDP is being measured by expenditure. Various categories of expenditure are recorded as follows: Households’ spending on consumption = $100bn, Firms’ spending on capital goods = $15bn, Firms’ addition to inventories = $1bn, Government spending on services = $10bn, Government spending on capital goods = $2bn, Government transfers (social security etc) = $10bn, Exports = $12bn, Imports = $10bn. What is the correct estimate of GDP?