Luft Inc.'s inventory balance, which covers 200 days of sales, amounts to 200,000. An analyst believes that the optimal level of inventory covers XXX days of sales. The analyst adjusts Luft Inc.'s financial statements by recording an inventory write-down for 40% of the inventory that is deemed excess inventory. This results in a negative effect of 17,500 on Luft Inc.'s net income. The tax rate is 30%.

Based on the information above, what is the days of sales of the optimal level of inventory?