Please show detailed steps. Thank you.

9. (20 pts) In a single time-step binomial model, suppose A(0) = 50, A(1) = 55, S(0) = 100, and with probability p= 0.3; S(1) = 90, with probability 1-p=0.7. | 140, (9a) (10 pts) Find the one time-step return r on the risk-free asset, the one time-step return K on the stock, and the risk-neutral probability p*. (9b) (10 pts) Find the time zero price P(0) of a put option with strike price K = 120 and exercise time T = 1