i need help with these 4 questions, mainly 1&3.

If a group of VCs is investing $10M in a Pre-money valuation of $50M, what is the post- money valuation and what percentage is the group of VCs getting? VCs prefer to have the stock option pool for employees be included after the round of financing. True or False. Please explain your reasoning. An early employee received a stock option package worth a total 5% of the company's equity. She was on a 4 year vesting schedule with a 1 year cliff (monthly vesting). What percentage of the company's equity will she be able to keep if she resigns after 8 months? What percentage of equity will she keep if she resigns after 34 months? What is a SAFE and how is it different from a convertible note? Why did Y-Combinator come up with a SAFE