For this case we have the following expressions:
[tex]-4.2 +3\\2.5x - 6[/tex]
To add both expressions, what we must do is add similar terms.
We have then:
[tex]2.5x + (-6-4.2 + 3)[/tex]
Rewriting we have:
[tex]2.5x-7.2[/tex]
Answer:
The sum of both expressions is given by:
[tex]2.5x-7.2[/tex]