Greetings from Brasil...
According to the statement of the question, we can write the following equation:
5 - 2X = 2X - 5
solving this equation to find X (the desired number)
- 2X - 2X = - 5 - 5
- 4X = - 10 · (- 1)
4X = 10
X = 10/4
X = 5/2
or
X = 2.5