What text connection is used in the following: a paycheck is to employee like an "a" is to a student

The connection used in the sentence is an analogy.

Analogy means comparison or relationship between various things, reasons or concepts; compare or relate two or more beings or objects through reason; pointing out general and particular common characteristics that allow to justify the existence of a property in one, from the existence of said property in the others.

In this case, the paycheck and the "A" are similar objects of desire for the employee and the student, since both carry out an activity to obtain them; so the connection is an analogy.

it continues in business