So since infantry get a 25% bonus against vehicles, and vehicles get a 25% bonus against tanks is this a good army build
60 ranged beam infantry, 30 ranged explosive vehicles and 20 ranged concussive tanks and also 50 short ranged concussive tanks.
This is just a general build against no particular opponent. Is it a well balanced build? Infantry will destroy vehicles due to bonuses and vehicles will destroy tanks.
Or is this build quite costly in terms of resources?

Nooo, only build one chassis type. If you build all 3 you will take 100% damage from the enemy while they only take a fraction of the damage from you. Or if you only use each chassis as its own army then your army will be much smaller than everyone and still you will suffer. Build only one chassis per era.

Ok I shall stick to tank build ratio 3:7
Thanks

I am fairly new at this game but I have heard about this 25% bonus xp for inf against veh, veh against tanks and tanks against inf. I have tried so many times in the battle simulator to see this xp bonus, for instance if I put 1 apc tanks against 3 concussive inf (1 arm, 1 dam, and 1 ran) the tank always gets destroyed, why is this?

The bonus that tanks have on inf is not like the others. It is not a straight 25% "boost" in damage. Also I should point out the "bonus" to damage is actually taking away from the enemies hp not increasing your ap.

But even then shouldnt to 1 concussive apc tank still be able to destroy the 3 concussive inf?

I cant get my head around how the tank always losses in that battle, I use infantry because I think numbers are better and I can build more each tick with the resources I gain, but I am always hesitant about going into a fight even when I know I will win because of the battle simulator.

I think u're mistaken, I just did a battle sim and the concussive apc tank was able to kill all 3 concussive inf, 1 armor, 1 damage, 1 range

First, concussive inf will lose to concussive tanks because the inf will only do 25% damage as opposed to the 100% damage of the tanks. Secondly you are building more number wise but still 1 squad is 30 when 1 squad of tanks is 10. The squads cost the same amount and are equal in power.

Ok I have rechecked it and now it is saying that the tank wins, It honestly said that the tank would loose against 3 concussive inf before. Maybe it was a glitch LOL, sorry to have wasted your time.

Not a waste of time, the more we can teach other players the better the community is. Glad to answer any questions you may have.