I have to add er to firefight. Is it firefighter or firefightter? Why

I know is firefighter but I have to explain why?
Help please

it is "fierfighter" because that would be the correct way of spelling it, if you said "firefightter" that would make no sense because there is no reason to add an extra "t" to the word...

because gh is two consonants

http://www.howtospell.co.uk/doubling-up-rule

The correct word after adding "er" to "firefight" is "firefighter."

To explain why, let's break down the process:

1. Start with the base word "firefight."
2. To form the comparative adjective, we add the suffix "-er" to indicate someone or something that does or is related to the action described by the base word. In this case, "fight" is the base word.
3. When we add "-er" to "fight," we get "fighter." This word refers to someone who engages in fighting.
4. Finally, we combine "fire" with "fighter" to form the compound word "firefighter," which refers to someone who fights fires.

Therefore, the correct word is "firefighter" because it accurately represents the role of someone who fights fires.