I think the answer choices didn't copy/paste properly. The divided by sign didn't come through. I think they all come through as equal signs.
The answer should be:
n = (168-18) ÷ 25.
Just in case my divided by sign doesn't display properly, it should be:
n = (168-18) divided by 25.
I think that's what A is supposed to be but it didn't come through correctly in the question.