Exactly how to find the cov(Rd,Re) in this question

A pension fund manager is considering three mutual funds. The first is a stock fund, the second is a long-term bond fund, and the third is a money market fund that provides a safe return of 6%. The characteristics of the risky funds are as follows: The correlation between the fund returns is 0.13 . You require that your portfolio yield an expected return of 11%, and that it be efficient, that is, on the steepest feasible CAL. Required: a. What is the standard deviation of your portfolio? b. What is the proportion invested in the money market fund and each of the two risky funds