Economic equilibrium is defined as a state of the world where economic forces are balanced and in the absence of external influences the values of economic variables will not change. This is the point where the quantity demanded and the quantity supplied is equal. Thus, they are balanced and there is no profit nor any loss. To solve for the equilibrium price, you have to either plot the supply
. and demand curves, or solve for their equations being equal. The explanation on how to calculate equilibrium price and quantity can be found here: http://www.brainmass.com/homework-help/economics/cost-benefit-analysis/203229.