Promotion Bonuses Accumulate How?

[DagHammarskjol]

In WoundedKnight's strategy guide for beginners, he says

An initially mediocre unit with 3 city attack promotions (+20%, +25%, +30%) receives a +85% bonus against cities...

How does that math work?

I would have thought that a unit with 3 city attack promotions gets +30% bonus against cities. I didn't figure that the bonuses add up, I figured the new bonus replaces the old bonus. But am I wrong?

Even if I'm wrong and the bonuses add up, how do we get 85% from 20, 25, and 30%? Add those numbers together and you get 75%. And if you take 130 percent of 125 percent of 120 percent of X, you end up with 195 percent, or in other words, a total bonus of 95%.

Whence 85%?

-Kris

 

[Solver]

They add up. It should be 75%.

 

[Lexad]

And it is not added to attacker's strength, it diminishes defender's. Go for Military Academy section, it's there.

 

[6K Man]

Maybe the strat guide was referring to Swordsmen?