Question

Carl is boarding a plane. He has 222 checked bags of equal weight and a backpack that weighs 4kg. The total weight of Carl's baggage is 35kg

Answer 1

Well first of all, 'kg' means mass, not weight.

If the total mass of all his baggage is 35 kg, and the mass
of his backpack is 4 kg, then the combined mass of all of his
checked bags is  (35 - 4)  =  31 kg.

If all of his checked bags have the same mass, then the mass
of each one is

                        (31 kg / 222 bags)  =  139.64  grams/bag   (rounded)