Example 4.4 could be more clear, it is not strictly wrong, but could be better, i.e. have weights on the right side of the inequality, i.e.

$$ VaR^{5\%}(0.5 X+ 0.5 Y) \approx 50 > 0.5 VaR^{5\%}(X) + 0.5 VaR^{5\%}(Y) = 0+0. $$