a$.$ What is the expected return of security $A$

b$.$ What is the beta of security B

$8\%=2\%+b**(10\%-2\%)$

$6\%=b**8\%$

$0\mathrm{.}756\frac{\%}{8}\%=b$

c$.$ Consider a port that contains sec $C$ and the risk free asset. The port weight is $-1\mathrm{.}0$

i$.$ What is the portfolio weight for security $C$

Please help me solve C i and explain it