Adding and Subtracting

You can only add fractions with the same denominator. 1/4 + 2/4 = 3/4 — just add the numerators. Different denominators? Find a common one first. 1/3 + 1/4: the lowest common denominator is 12, giving 4/12 + 3/12 = 7/12. The LCD keeps numbers small and computation clean.

Subtraction follows the same rule. 5/6 - 1/4: common denominator 12 gives 10/12 - 3/12 = 7/12. The denominator stays the same; only numerators move. Always simplify your answer — 8/12 becomes 2/3 by dividing both parts by their greatest common factor, 4.