How do reduce fractions using divisibility rules?

To reduce fractions using divisibility rules, first identify the greatest common divisor (GCD) of the numerator and denominator. This can be done by checking for common factors, such as 2 for even numbers or 3 by summing the digits. Divide both the numerator and denominator by their GCD to simplify the fraction to its lowest terms. For example, to reduce 8/12, since both are divisible by 4, divide by 4 to get 2/3.