Fractions have a top number, which is called the numerator, and a bottom number, which is known as the denominator. This combination of numbers represents how a part relates to a whole. If you have a negative number or variable in the denominator of a fraction, the fraction is not in simplest form, according to traditional mathematics. To state the fraction properly, you must take measures to convert the negative value in the denominator to a positive one.

Write the fraction. For example, you might have 5/-10.

Multiply the numerator and denominator of the fraction by -1/-1. This is the same thing as multiplying the fraction by 1, and 1 times any number is that number. In this example, you would multiply 5 by -1 to get -5 and -10 by -1 to get 10. Therefore, the fraction would become -5/10.

Reduce the fraction to simplest form if necessary. In this example, you can divide -5 and 10 by 5, leaving -1/2 as the final answer.