Relate grouping problems where the number of groups is unknown to multiplication equations with a missing factor, and to division equations (quotative division)

What this means, in plain words

A factor is a whole number that divides into another exactly, with nothing left over.

Algebra uses a letter to stand in for a number that is not known yet.

This is problem solving: the maths is met inside a situation, so the first job is working out which operation the question is asking for.