Bonjour, Est-ce que qlqn peut m’aider à faire ce devoir, j’ai besoin d’aide sur question b. s’il vous plaît Merci d’avance

Hello I would like to ask you a couple of questions regarding cctv:
How does they work??
Can they be hacked easily??
How much does they cost??
And for my opinion cctv should be installed in every school in case a robbery happened or a conflict between students and especially in exams rooms in case there was a cheating case