The Pearson square or box method of balancing rations is a simple procedure that has been used for many years. It is of greatest value when only two ingredients are to be mixed.

hi dear 

https://www.dairyscience.info/newCalculators/pearson.asp

Dear Dr. Esraa

The Pearson Square or Rectangle Method, also called Pearson's Square or Pearson's Rectangle, is a simplified method for solving a two variable simultaneous equation. While it is being used here with milk it is widely used in standardisation calculations for sausage manufacture, jam manufacture and blending alcoholic drinks; anywhere where it is necessary to calculate the amounts of two components that need to be mixed together to give a final known concentration.

thanks dr.hassan