The easiest mathematical example, which not everyone can do

The easiest mathematical example, which not everyone can do

At first glance, the example we have prepared for you seems surprisingly simple. And it is. But not for all mathematics geniuses.

This problem has already appeared on the internet and divided readers into two camps. So many different answers have been given!

How many ways are there to solve this example, and which answer is correct? You will have to figure that out today.