For this case, we have that by definition, the difference is represented by the mathematical sign "-", also called signs of subtraction or sign of subtraction.
Then we discard options A and B.
We have the option C: [tex]6 + x-9[/tex]
It contains a sign of addition and also refers to three terms.
Finally, in the last option, we have a difference of two terms.
[tex]6x[/tex] is the first term
[tex]9[/tex]is the second term
ANswer:
Option D
