Fraction arithmetic

Addition and subtraction

In order to add or subtract fractions you need to have the same denominator (below the line). Then you can add or subtract the numerators (above the line).

You should change each denominator to the LCM (lowest common multiple)of the denominators, and multiply the numerators by the same number. Remember that if two numbers are the same then the LCM is also the same. If one number goes into the other, then the LCM is the bigger number.

If you aren't confident about LCM's then you can just multiply the first fraction, top and bottom, by the denominator of the other fraction. Then multiply the second fraction by the denominator of the first fraction. However this may give you a number which needs to be simplified.

When the denominators are the same, just add or subtract the numerators.

For example, -mathformula not MarkupType-
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