May I have the while soultion for question 3(all the sub Q as well) Thanks a lot

You are provided with historical data on the risk characteristics of TAMC and Kaisa. The correlation coefficient of TAMC's return versus Kaisa's return is 0.37. Assume the standard deviation of returns on the market was 15 percent. (a) What is the standard deviation of a portfolio invested half in TAMC and half in Kaisa? (b) What is the standard deviation of a portfolio invested one-third in TAMC, one-third in Kaisa, and one-third in Treasury bills? Please input your response in percent rounded to two decimal points (but without the percent sign)