DCF Case study

I am trying to build a dcf given an income statement, a balance sheet, and some assumptions.

I’m running into some trouble with depreciation. Is it acceptable to just use straight line depreciation? I tried this but it did not match the accumulated depreciation listed on the balance sheet.

I’m also pretty lost on how to calculate working capital as there is only information on assets and such for the one year on the balance sheet. Should I be extrapolating this?

Thanks for any help.