Addition and Subtraction
To add or subtract two or more numeric fractions, we carry out two steps. Step one: rewrite each fraction to an equivalent fraction, making sure that both of the equivalent fractions have the same ("common") denominator. Step two: add the numerators of the two fractions that share the same "common denominator". This process is illustrated in the examples below.
Example 1 To add 
+ 
, we begin by thinking of a “common denominator”. In this case, we note that 4 × 3 = 12 and so we rewrite each fraction with 12 as the "common denominator."
Thus,
becomes
and becomes
Then
+ =
+
= 
Example 2
In the same way, to perform 
- 
you
must express these fractions as 20ths.
Thus,
- =
-
= 
Example 3
To evaluate 
- +
, we
proceed according to the examples above.
Thus,
- +
= 
- 
+
=
Before proceeding to the exercises, ensure that you have some paper and
a pencil handy.
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