The percentage increase in income differs from the percentage increase in sales, when there is others operating income added to the sales amount. Example: Rent income is recorded as other operating income if you are selling stationery as a registered company to sell stationery items to a stationery shop or more shops as a supplier for profits. Thus, your sales amount will be recorded in the income statement when your sale of your inventory(stationery) plus mark-up on cost of purchased inventory, successfully sold. Either, in credit form or by cash form, both are to be added to be come a total sales amount.