Who knows how much money a salesman of surveying and mapping instruments can earn?

It depends on how many customers you have;

Ordinary salesman: basic salary 1000 points+profit 20% commission.

If you just entered the business, it is estimated that you can earn 20,000 to 30,000 a year. If you are an old salesman, you can earn 200,000 to 300,000 a year.