how to solve part 1 and 2

Problem 18 Intro The return on Samsung stock has a standard deviation of 31% and the return on Toyota stock has a standard deviation of 17%. Their covariance is 0.02108. Part 1 Attempt 1/10 for 10 pts. If you invest 20% in Samsung and 80% in Toyota, what is the variance of the portfolio? 4+ decimals Submit | Attempt 1/10 for 10 pts. Part 2 What is the standard deviation of the portfolio? 3+ decimals Submit