Unit 1B: Rational Numbers
Part 3: Problem Solving with Rational
Numbers in Fraction Form
Objectives
•  Add and Subtract Rational Numbers in
Fraction Form
•  Multiply and Divide Rational Numbers
in Fraction Form
•  Apply Operations with Rational
Numbers in Fraction Form
Add & Subtract Rational Numbers in Fraction Form
To add and subtract fractions, we need to find
the Lowest Common Denominator (LCD)
between the two fractions
Note: When adding or subtracting:
•  always move the negatives to the top.
•  always convert mixed fractions to the
improper fraction form first.
Examples:
1. 2 1
−
5 10
2.
3 1
− +
4 5
1 " 9%
3. 2 − $ −1 '
2 # 10 &
Multiply and Divide Rational Numbers in Fraction Form
Recall
Multiplying & Dividing Integers Rules:
(+)(+) = +
(+) ÷ (+)= +
(–)(+) = (+)÷ (-) = –
(+)(–) = (–) ÷(+) = –
(–)(–) = +
(–) ÷(–)= +
Multiplication
Multiplying Fractions:.
•  When multiplying fractions, it is best to simplify the fractions first
before multiplying
•  If a negative is in front of the fraction, take it to the numerator
•  Multiply the numerators and multiply the denominators
Examples:
# &
1. 3 ⋅ % − 2 (
4 $ 3'
3 # −2 &
⋅% (
4 $ 3'
3⋅ −2
4⋅3
−6
=
12
1
=−
2
=
2. Determine Each Value
a) 2 " 1 %
− $− '
5# 6&
b)
3 1
− ⋅5
8 3
Division
•  When dividing fractions, we multiply the reciprocal
of the divisor.
•  Ensure that our fractions are in the improper form
before simplifying.
Examples:
1. 3 ÷ "$ − 11 %'
2 # 4&
3 " 4%
= × $− '
2 # 11 &
3× (−4)
=
2 ×11
−12
=
22
6
=−
11
2.
1 1
−2 ÷1
8 4
Order of Operations on Rational Numbers in Fraction Form
BEDMAS
**Make sure you understand the difference between
the rules of addition/subtraction of fractions and
multiplication and division of fractions
Examples:
1. 1 " 2 1 %
3
$ − '+
3 # 5 2 & 10
What is the first operation we will do?
2.
3 5 3 1
÷ − ÷
4 8 8 2
Assignment
•  MathLinks 9 Textbook
•  Pg 67-70
#5 (calculate only), #6 (calculate only), #7 (calculate
only) #8 (calculate only), 19, 21