It hurt the south for a while, slave labor was good for the south's economy but bad for competition up north because nobody could find a job if all the slaves worked for free. The removal of slavery cemented this competition-based method into America.
The equilibrium is the price that comes out from adding all the direct related costs in producing the good or service. To this total you have to add the indirect costs, for example, taxes, salaries, etc. Add up both results and you will have the price.
The equilibrium price is the price that covers all your expenses, both direct and indirect. With this price you do not lose nor earn any money.
Because Italy was mostly divided into strong and independent city states it had a very special status throughout the renaissance period. The individual city states were able to conduct trade with other nations independently of each other. Here, different kings had different notions on how their relationship with Italy should be; which was best seen exactly in the way how the king of Spain and king of France treated the city states and Italy as a whole.
conflict ended with the country split into a Communist North and a pro-Western South is the answer.