can someone show work and explain why the answer is 80?

Annual demand for a particular halogen bulb is D= 3,600 at a business that operates 300 days per year. The cost per order S = $25 and the holding cost per unit per year is $2. If the lead time is 5 days, and demand during lead time follows the empirical distribution given in the following table: Number of Units Probability 30 .10 40 .10 50 .15 60 30 70 .15 80 .10 90 .10 What is the reorder point is required to ensure a 90% service level? Select the correct response (rounded to a whole number) from the following: Select one: O a 20 Ob. 40 G60 d80 O. 90 Clear my choice