Final answer:
Foreigners purchased $400 billion of the country's assets.
Step-by-step explanation:
To find out how many assets foreigners purchased, we can use the formula:
Assets purchased by foreigners = Total foreign assets - Initial foreign assets
In this case, the total foreign assets are $600 billion and the initial foreign assets are $200 billion. Plug the values into the formula:
Assets purchased by foreigners = $600 billion - $200 billion = $400 billion
Therefore, foreigners purchased $400 billion of the country's assets.