Answer:
12,000 dollars are invested in A.
Explanation:
This portfolio Beta is calculated
[tex]Stock.A.Beta * invested.A + Stock.B.Beta * invested.B + Risk.free beta * invested.Rf[/tex]
Replacing the text with data (Beta of Riskfree = 0)
[tex]1.29 * A + 0.9 * B + 0 * Rf = 0.58[/tex]
Where, as Rf = 0.5, then A + B = 0.5, then A = 0.5 - B