Chapter 11 exercise problem: i'm pretty sure i know how to solve this, but this can't hurt (answers in excel format please)

1/The Belgian Vandeputte Group has the following operating structure: sales 100, raw materials used in the business 30, direct production costs 40, administrative costs 20. Operating cycle: raw materials inventories 15 days, length of production cycle one month, inventories of finished products 15 days. Payment terms: suppliers two months, customers one month, other costs paid in cash. Assuming zero VAT, calculate working capital in days of sales. The production cycle lasts one month, which means that in-progress inventories represent one month of raw materi- als and 15 days of production costs