1. Depending on the size of the number or the range of letters, for example: | 1- root number 3|= root number 3- 1.
|3. 14-π|=π-3. 14
| 3-a |-| a+2 |(-2 & lt； a & lt3)
=3 -a - (a+2)
If there are no conditions and letters, discuss them in sections.