What is the justification for the step taken from line 2 to line 3?

Taking algebra two apex courses and need with these questions

Question 1 of 10 2 points different groups of 50 graduates of an engineering school were asked the starting annual salary for their first engineering job after graduation, and the sampling variability was low. if the average salary of one of the groups was $65,000, which of these is least likely to be the average salary of another of the groups? o a. $64,000 o b. $65,000 o c. $67,000 o d. $54,000

Determine which postulate or theorem can be used to prove that lmn =nmo