i need the calculations. the percentages are the answers in the back of the book

7. Calculating Returns and Standard Deviations Based on the following information, calculate the expected returns and standard deviations for the two stocks. State of Economy Probability of State of Economy Rate of Return if State Occurs Stock A Stock B -.30 Recession Normal Boom .10 .50 .40 .02 .10 .15 .18 .31 7. A: 10.55%; 4.25% B: 15.35%; 19.94%