There are two rules to remember when adding or subtracting fractions. The fractions need to have a common denominator. This means the denominator has to be the same. You only need to add or subtract ...

Click to see a step-by-step slideshow. STEP 1: Write the question and circle the key information. Draw a bar and split it into 12 equal segments: the denominator of the fraction. Label the end '/12'.

† Grupo de Química Analítica e Quimiometria, Department of Chemistry, Federal University of Juiz de Fora, 36036-900 Juiz de Fora, Minas Gerais, Brazil ‡ Laboratory of Research and Development of ...