I'm considering a Probit model for the probability that a student will finish the course based on their hours of study, age, sex, origin, how they passed the previous course and labor market situation for students.

Code:
probit finish hours age women inmigrant previous_courses
Now with these estimates, I have to compute the number of hours of study necessary so that the probability of completing the course of a student who works is the same as that of another student with identical characteristics but who does not work.

I know I have to use the command
Code:
margins
but I can't figure out how. Any clue?

Thanks in advance!