Children may find the easiest way to work this out is by using the column method, where all the numbers are placed in a column, one on top of the other. It is vital that they remember that the decimal points of each number must line up. Once they’ve worked out using pencil and paper, let them check on a calculator as using decimals accurately on a calculator is an important real life skill too.
In the simplest cases, the two fractions will already have a common denominator. In this case, add the numerators and then reduce the resulting fraction.