84: x=9 ( ост 3)

I assume you are looking for the remainder when 84 is divided by 9.

To find the remainder when one number is divided by another, you can use the modulo operator (%) in most programming languages. In this case, if you divide 84 by 9 using the modulo operator, you will get a remainder of 3.

Therefore, when 84 is divided by 9, the remainder is 3.