I need the formula, and the solution step by step.

A portfolio has an expected return of 13.4 percent. This portfolio contains two stocks and one risk-free security. The expected return on Stock X is 12.2 percent and on Stock Y it is 19.3 percent. The risk-free rate is 4.1 percent. The portfolio value is $48,000 of which $10,000 is the risk-free security. How much is invested in Stock X? A. $21,548.19 B. $19,514.14 C. $18,478.87 D. $22,200.14 E. $16,904.72