Please help me with these exercise questions as I seem to be a bit stuck. Thank you in advance for your help and all that you tutors do.

1. A company has 200mm of debt, 50mm of cash, 25mm shares of stock trading at $10. It has operating income (EBIT) of 40mm and D&A of 10mm. What is EV/EBITDA and debt/EBITDA?
2. Ligand Pharmaceuticals (LGND) has a P/E ratio of 45 while Pfizer (PFE) has a P/E ratio of 14.5. Based on the above, why are the P/E ratios so different?
3. Which of the following are parts S,G&A for General Motors?

Cost of purchasing assembly line robots

Cost of steel and aluminum

Salaries of workers on assembly line

Salaries of marketing/advertising people

Interest expense on bonds

Cost of insurance for headquarters

Federal income tax

Salary of CFO