What takes a licking and keeps on sticking crossword?

Why are the majority of the world's economies mixed? what may happen to the "pure" types of economies (traditional, socialist/command, market capitalist) when they incorporate elements from other economic models?

In a small, closed economy, national income (gdp) is $350 million for the current year. individuals have spent $100 million on the consumption of goods and services. they have paid a total of $60 million in taxes and the government has spent $75 million on goods and services this year. use this information and the national income identity to answer the questions. how much does the economy spend on investment?

What happens after a star goes supernova? just wondering! [tex]supernova [/tex] answer asap i really wanna know!