Whether the answer is positive or negative depends on the number of positive and negative values in the question. The rules are exactly the same as to whether an answer is positive or negative. In the case of fractions, the rules for multiplying fractions apply as well (the numerators in the expression multiply to produce the product's numerator; the denominators in the expression multiply to produce the product's denominator) and the answer should be reduced to lowest terms.
If there is an odd number of negative terms, the answer will be negative.
If there is an even number of negative terms, the answer will be positive.