Calculate depreciation and net investment during 2018.

An economy’s capital stock was $46.3 billion at the end of 2016, $46.6 billion at the end of 2017, and $47.0 billion at the end of 2018. Depreciation in 2017 was $2.4 billion, and gross investment during 2018 was $2.8 billion (all in 2007 dollars).