The rule for adding and subtracting fractions involves finding a common denominator and then performing the operation based on that denominator. Here are the step-by-step instructions: Find a common denominator: The denominators of the fractions you’re working with need to be the same. If the denominators are already the same, you can skip this step. Otherwise, you need to find the least common multiple (LCM) of the denominators. The LCM is the smallest number that is divisible by both denominators. Convert the fractions: Once you have a common denominator, you need to convert each fraction so that it has that common denominator. To do this, you multiply both the numerator and denominator of each fraction by the same number that will make the denominator match the common denominator. Perform the operation: For addition, you add the numerators of the fractions together and keep the common denominator. For subtraction, you subtract the numerators of the fractions and keep the common denominator. Simplify, if necessary: After performing the operation, you may need to simplify the resulting fraction. To simplify a fraction, find the greatest common divisor (GCD) of the numerator and denominator, and divide both the numerator and denominator by the GCD.