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Do you need a common denominator to add or subtract fractions? How do you add fractions? 5 7 = + 2 3 How do you subtract fractions? 5 7 = 3 2 Example 1 A] B] C] Find the Least Common Denominator (LCD) , , Find the Least Common Denominator of these three fractions. Example 2 A] B] C] Adding/Subtracting with like denominators A] 3x2 x ­ 2 + 3x ­ 2 3x ­ 2 B] 3x2 ­ 3x ­ 2 x ­ 2 3x ­ 2 Example 3 Adding/Subtracting with different denominators Step 1: Find the least common denominator (LCD) Step 2: Multiply each fraction, top and bottom, by any factor missing from the LCD. Step 3: Distribute and add/ subtract the numerators. (Don't forget to distribute the negative if you are subtracting!!) Step 4: Simplify. (Don't forget to check if anything will factor further!!) A] B]