They each have two chocolates so those numbers of chocolates are the same.
Not counting the tubs, Arthur has one bag of chocolates and 25 loose chocolates; Oliver has two bags and 7 loose. If they both have the same total number of chocolates, then the difference in the number of loose chocolates they have (25-7=18) must be the number of chocolates in a bag.
There is no information given, in the problem as you show it, that allows us to determine the number of chocolates in a tub.
Answers: chocolates in a bag: 18. chocolates in a tub: unknown.