It is ont with they (ils or elles) and a with he, she, it or il, elle, on
When is it "a" and when it it "ont"?
i have -> j'ai
You have -> tu as
He/she/it has -> il/elle a
we have -> nous avons
they have -> ils/elles ont
why is it not "une livre"? isn't livre feminine?
No, livre is masculine.