Explanation:
all human individuals are "people" - adults and children.
so, there are
23 + 45 = 68 people
in the theater.
each row seats 9 people.
how many rows ?
how often fits the capacity of one row (9 people) into the total capacity ?
68/9 = 7 full rows and 5 people remainder.
that means
we need 8 rows.
7 of these rows are full, and the 8th row has only 5 people.