please show all the steps one by one to make me understand well. Do not want answers on Chegg already. it's hard to understand them

a) State of the Economy RA RB Rc Depression -20% 5% -5% Recession 10% 20% 5% Normal 30% -12% 5% Boom 50% 9% -3% You planned to invest in the stock market in any one three stocks: Stock A, B, and C. As you are aware that, the economy is expected to behave according to the table above and states of nature have equal probabilities (25%). Required to calculate: i) Expected return ii) Variance iii) Standard deviation