Question

You have a mortgage payment of $1,248.90/month. Using proportions, what is the minimum amount you must have in realized income per month to keep your housing expense in the acceptable range

Answer 1

The answer depends on a large number of factors. In general, the mortgage payment should be less than a percentage of the gross family income. Depending on the source, this percentage can range from 25 to 33%. However, in real life, it also depends on what other financial obligations are existing, size of family, location (city, country), existing debt (car payment, credit card balance,...)
The academic answer depends on the recommended percentage from your textbook or your teacher.