The sum of two rational numbers will always be rational. A rational number is a number that can be expressed in the form a/b with b ≠ 0. So, if we can prove that the sum of two rational numbers has a denominator, we have proven this statement. Since any rational number can be written as a/b, we can write sum of two rational numbers as a/b + c/d. We can make this ad+bc/bd. Since we proved that the sum of two rational numbers has a denominator, we also prove that their sum is rational.
