Go with the Flow!
Adding and Subtracting Fractions
Are there any mixed numbers?
Convert any mixed numbers to
improper fractions.
e.g. 4
2
=
3
e.g 4
2
3
Are they all like fractions? (Do they have
the same denominator?)
13
e.g.
3
3
4
+𝟕
𝟕
Because 3 x 4 + 2 = 13, and the
denominator stays the same.
Make them like by finding a common denominator, and
changing the numerators to create equivalent fractions.
“What you do to the bottom, you must do to the top”
Yes
e.g. 5 and 3 both go into 15 evenly, so use 15 as the new
denominator (the easy way is to multiply each fraction
by the other denominator)
Add the numerators (top),
and keep the denominators
(bottom) the same.
2
1
2×3 1×5
6
5
11
+
=
+
=
+
=
𝟓
𝟑
5 × 3 3 × 5 15 15 15
e.g.
6
15
+
5
15
=
11
15
Is the fraction ‘proper’? (the top number is
smaller than the denominator)
e.g. Proper:
Yes
10
11
Improper:
14
11
or
11
11
Change it to a whole or mixed number
e.g.
Is the fraction in lowest terms? (If the
numerator and the denominator share a
common factor, then they can be reduced)
𝟏𝟒
𝟏𝟏
11
4
𝟒
= 11 + 11 = 𝟏 𝟏𝟏
11
11
or
=1
Divide the numerator and denominator by
the ‘Greatest Common Factor’ (GCF) to
reduce to lowest terms.
4
e.g.
12
=
4 ÷4
12 ÷4
=
1
3