Looking up...
Elle est très forte en maths.
She's very good at math.
Physically or mentally strong; loud.
Elle est très forte en maths.
She's very good at math.
Agrees: fort, forte. Être fort en = be good at.
As an adverb, loudly.
Parle plus fort, on ne t'entend pas.
Speak louder, we can't hear you.
Adverb use is invariable.
From Latin fortis (strong).