Suppose there are two assets investors can buy in the market: a government bond (denoted by A) which yields a guaranteed return of 2% (so this is a risk-free option), and shares of a company (denoted by B) which yield a return of 10% with probability 0.5, while with probability 0.5 the return is 0 :

1. What is the expected return of the bond? What is the expected return of the shares? What are the variances of returns
2. If you spend half of your wealth buying the bond and the remaining half buying the shares, what is the expected return of your portfolio? What is the variance of the return of this portfolio?
3. Now suppose instead of investing in the risk-free government bond youhave an option to buy shares of another company, let's denote themby C, which yield 10% return when the return to B is 0, and yield 0 when shares B yield 10%. Suppose you decide to go for a portfolio one half of which is the shares B and the other half is shares C. What is the expected return of the portfolio in this case? What is the variance?

Please explain this step by step, thanks !