Answer: Trade Deficit ($10 Billion).
Explanation:
C=40+0.8Y
Ig=$40 billion
X=$20 billion
M=$30 billion
where,
Y - GDP
C - Consumption
Ig - Gross investment
X - Exports
M - Imports
Balance of trade or Trade balance = Exports - Imports
Since, Imports are greater than the exports, so the nation is experiencing a trade deficit.
Trade deficit = Imports - Exports
= $30 - $20
= $10 billion