Hi everyone, I would be super grateful if you could help me with this question. I tried to solve it myself, but it just won't add up. Please help!!

A company is workin on the market of perfect competition. Its cost function TC=Q^2-4Q+64 and demand function on the product that company produces is Q=400-20P. Calculate:
a. optimal quantity of production, at which company maximizes profits
b. market proce at which company maximizes profits
c. break-even price of this company
d. total revenue at profit maximazation