The solution of problems with short-sightedness and far-sightedness was long ago. It is enough to use contact lenses or points. At glasses wearing there can be certain problems. Glasses of glasses can be soiled, broken, lost. One more problem is added to cold season to this list: points begin to mist over.

The Efficiency (E) is an indicator of efficiency of any system, whether it be the car engine, the car or other mechanism. It shows how effectively this system uses the received energy. It is very easy to calculate efficiency.

Efficiency (efficiency) – the dimensionless size characterizing overall performance. Work is force influencing process for some time. Energy is spent for action of force. Energy invests in force, force is put in work, work is characterized by effectiveness.

Equilibrium volume implies such volume of a proizvodyostvo at which equality of cumulative expenses and volume of the made products is provided. It is also called equilibrium GDP (or the output) which includes cumulative expenses which are sufficient for realization of a certain volume of production activity.