On Windows 10, the $WINDOWS.~BT folder contains your previous Windows installation. These files are used to downgrade to a previous version of Windows, or a previous build of Windows 10.
Aggregate Demand and Supply. The macroeconomic model for Aggregate Demand and Aggregate Supply differs from the microeconomic model in the fact that the AD/AS model represents all goods and not just one single good. It takes into account the price level of all goods as well as the overall aggregate output of the economy. Aggregate Demand (AD) represents the demand side of the economy. Long-run Aggregate Supply (LAS) represents the most output that an economy can sustain. Short-run Aggregate Supply (SAS) represents the supply of the economy in the short run.
The Aggregate Demand Curve. The aggregate demand curve shows, at various price levels, the quantity of goods and services produced domestically that consumers, businesses, governments and foreigners (net exports) are willing to purchase during the period of concern.