Answer: $500 billion
Explanation:
The country's savings will be explained below:
Savings = Domestic Investment + Net Capital Outflow
where, the net capital outflow will be:
= exports - imports
= $100 billion - $400 billion
= $-300 billion
Therefore, the country's savings will be:
= Domestic Investment + Net capital Outflow
= 800 + (-300)
= 800 - 300
= $500 billion