Each country has a unique economic system to allocate its scarce resources. however, the economic system of most of the world's nations are a combination of the system and the system.

center planning ; Price.

Explanation:

the blank will be filled with central planning; Price.

center planning system is the system in which the decision is taken by the central government.  

Most of the world's nation believe in the central planning system for economic decisions.

The price system is the system in which money is used for the valuation and distribution of goods and services.      

classical republicanism, also known as civic humanism, is a form of republicanism  developed in the renaissance inspired by the governmental forms and writings of  classical  antiquity, especially such  classical  writers as aristotle, polybius, and cicero.