forwhat

R^2 = rho^2,

R^2 ==> systematic risk

1-R^2 or 1-rho^2 ==> unsystematic

 

for this specific question, rho=.7, therefore, R^2=.7*.7=.49, the systematic risk is .49, then you can get unsystematic risk is .51 under the assumption "total risk = systematic risk + unsystematic risk"