Now the parts of the inside ring and outside ring have the same size, and we can add the fractions! This is called finding the main denominator. The main denominator divides the rings into equal parts.
Agora as partes dos aneis interior e exterior teñen o mesmo tamaño e podemos engadir as fraccións! Isto é o que se chama achar o denominador común. O denominador común divide os aneis en partes iguais.