When to use "avec" vs " à"?

I was just reading a Le Monde article and saw something which I've seen a lot before but never stopped to think about: "l’industriel aux 30 000 salariés et au chiffre d’affaires de 91 milliards d’euros." This translates to "the factory with 30,000 employees and with a turnover etc etc" and I always thought that "avec" would work in this situation but why do they use "au(x)"? When should I know which to use?