The fixed costs of Widget Limited are 210,000 and the variable costs are 15 per unit. Marketing forecast says Widget Limited is expected to sell 11,000 units at a price of 35 per unit. However, a recent marketing study suggests that for any additional advertising expenditure more items will be sold. Using CVP analysis explain at least how many extra items should be sold for each 40,000 advertising for the campaign to become a viable course of action