Accounting has its unique theory, as it is a type of social sciences; discuss this statement explaining main principles and assumptions of accounting.  

 Define accrual basis and cash basis of accounting then give numerical examples for each method and explain which of them recommended by IFRS.

Ibrahim has a sole proprietorship working in goods merchandising and he needs to choose an inventory costing method. Being an accountant, list methods Ibrahim can use and explain to him advantages and disadvantages of each method supported by numerical examples.