## How to add or subtract fractions?

It is very simple when the fractions are of same denominator. Then you just add the numerators.Examples:

And so on.

## And if the fractions are not of the same denominator?

Put them on the same denominator… You could use prime factorization to find out the kgV, or you simply try to find a number divisible by both denominators.Example: We want to calculate . A possible common denominator is . So we calculate:

.

Another example: We want to calculate . Of course, we could use as denominator, but if we take a closer look, we realize that is the kgV. So we just have to calculate

.

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