Examples of fundamental rule/principle of governing the planned and market economy system

Which choice best describes the general trend for the countries shown, for the period 2008 - 2010?

What is the rule relating the ratio of marginal utility to prices of two goods at the optimal choice? explain why, if this rule does not hold, the choice cannot be utility-maximizing.

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?