Answer:
The contributions of these transactions is a reduction to GDP by $500 in 2011 and an increase in GDP by $800 in 2012.
Step-by-step explanation:
GDP is the abbreviation for gross domestic product which is the monetary value of all finished products (goods and services) made within a country during a specific period (usually a year). In the determination of a country's GDP, imports are subtracted while exports or sales are added.
Therefore considering that Amy received a shipment of Valentine's Day cards in December 2011 paying a total of $500 and sold all the cards for a total of $800 in February 2012, the contributions of these transactions is a reduction to GDP by $500 in 2011 and an increase in GDP by $800 in 2012.