im lost so i divided 160k/400k the got a 40% and multiplied by 15000 to get 6000and then subtracted 5000 to get 1000

Ring, Incorporated's income statement for the most recent month is given below. Refer to the original data. The marketing department believes that a promotional campaign at Store P costing $5,000 will increase sales by $15,000. If the campaign is adopted, overall company net operating income should: decrease by $800 decrease by $5,800 increase by $5,800 increase by $10,000