Here's the rule for working with these things:
There are 3 signs associated with a fraction:
=> the sign of the numerator
=> the sign of the denominator
=> the sign of the whole fraction; (if the fraction were in
parentheses, this sign would be written outside).
-- You can change any 2 of them without changing the value of the fraction.
-- Changing any 1 of them changes the effective sign.
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Now, you said the fraction is negative.
So, let's start with the positive fraction, and see the different ways
that we could make it a negative fraction:
=> mark only the numerator negative
=> mark only the denominator negative
=> put parentheses around the fraction, and mark it negative outside
If you do any one of these things to a normal positive fraction,
it turns into a negative fraction.
Look at the choices you listed in the question:
-- in the numerator only ? Yes. That makes it a negative fraction.
-- in the denominator only ? Yes. That makes it a negative fraction.
-- both ? No. That makes it the same as a positive fraction.
-- put parentheses around the fraction, and a negative sign outside ?
Yes. This makes it a negative fraction.
-- it doesn't matter ? No. I hope you can see that it does matter.
Have I confused you ?
Is this more than you wanted to know ?