Carry On Baggage How Much Weight Can I Carry On Each Baggage On International Flight? And Carry-on Baggage That I Take On Board

How much weight can I carry on each baggage on international flight? And carry-on baggage that I take on board - carry on baggage

Hello.
I travel to China, but I have no idea how much weight can be made. I have two large suitcases and a backpack and handbag. Each of the two bags is about 40 lbs. My question is which law and policy on the weight of the passengers baggage? Hope you guys understand my question.