Consider the problem: 'In a game of marbles, Renu lost 4 marbles. She is now left with 7 marbles. With how many marbles did she start the game?' The above question is an example of a:

A mathematics teacher of Class II gives the following word problem on addition to the students: 'A bag contains 4 mangoes and 6 more mangoes are put into it. How many mangoes are there in the bag in total?' This type of word problem belongs to which of the following structures of addition?

A teacher wrote the number 308 on the blackboard and asked the children to read it aloud. A child said, 'It is thirty-eight.' Which of the following is the most appropriate strategy to rectify the error made by the child?