Hi all! I just started my journey to the world of poker, and I'm reading "Poker Foundations" by Cory Mikesell.

There are a Expected Value calculation examples in the beginning. In the example about passing drive license exam we can see this calculation: 0.95(600$)-0.05(300$)=555$ and explanation after. My question is about sequence. Is some constant here? Because if we change bets by places we'll have negative result: 0.05(300$) - 0.95(600$) = -555$, therefore author
shouldn't take a bet.

This question was born when I've tried to calculate expediency to take "Full coverage insurance packages" for rental car in my vacation.
Price without the package is 45€ Price with is 95€ The biggest amount I can lost in case of car accident is 500€. I estimate the likelihood of car accident in 5%. So we have: 0.95×(40€ how muchI can safe) − 0.05×(500€) = 13€
So... How can I interpret this result and am I right in my calculation? Because if I change values by places I'll have inversely proportional result.