what would be the standard deviation for a portfolio that consists of 50% macdonald's and 50% dell, in which investor only provided only 50% of the capital and borrowed 50% of rest of the required capital?

stdeviation %15 11 Market Dell McDonald's B (beta) 1.41 -0.31 77 Yearly standard deviation of return (%) dell 8 Mc Donald's 30,9 172