explain the goal of an economic system,how would you apply the goal to the less developed countries?

Any economic system aims to answer these three questions. ie it is the goal of ALL economic systems to answer them. Different economies answer them in different ways.

In a LDC, subsistence and primitive methods of production will determine “how”. “What” may be decided by needs but can be influenced by cash crops such as heroine. “For whom” will often be decided by barter.