7. Chancy can design a risky portfolio based on two risky assets, Chuck and Nancy. Chuck has an expected return of 15% and a standard deviation of 21%. Nancy has an expected return of 7% and a standard deviation of 11%. The correlation coefficient between the returns of Chuck and Nancy is 0.20. The risk-free rate of return is 4%. What is highest possible Sharpe ratio of Chancys portfolio?

The answer is: 0.5511

8. You put 40% of your money in a stock portfolio that has an expected return of 13% and a standard deviation of 20%. You put the rest of your money in a risky bond portfolio that has an expected return of 6% and a standard deviation of 10%. The stock and bond portfolios have a correlation coefficient of 0.23. Calculate the standard deviation of the resulting portfolio.

The answer is: 11.05%

The answers are corrects. I need help with the equations, on how to get those answers.