Answer:
Three roles of government in a planned economy:
*Planning economic activity: in a planned or command economy, the government actually plans the economy, in the sense that it determines the amount of goods and services to be produced an distributed over a period of time. In the Soviet Union for example, this period of time was of 5 years.
*Owning businesses: in planned or command economies, most or all firms are public, since private property usually does not exist in this type of economices. These firms tend to have a high degree of government control, where directly in the form of government ownership, or indirectly.
*Setting prices: a key characteristic of a planned economy is that prices are set beforehand. They are not left for the market to decide.