1. Review 3.5
11/12 + 7/12
5 2/5 – 3 9/5
-9b/18 + 7b/18
-5/21w – 16/21w

2. Adding/Subtracting Unlike Fractions
Objective: students will be able to find a common denominator. With that they will be able to add/subtract fractions with unlike denominators.

3. Least Common Denominator
Least common Denominator (LCD): Lowest shared multiple.
8, 12
2, 7

4. Find the least common multiple
2, 9
4, 5
10, 15
6, 7

5. Information Different denominator Ex: -2/3 + 3/4 5/11 – 2/3 Find LCD
Change numerator
Follow other addition rules
Ex: ¼ + 2/3
3/12 + 8/12 = 11/12
Ex: -2/3 + 3/4
5/11 – 2/3

6. ST: Examples
7/10 – 4/5
-4/6 + 7/9

7. Solve
2/5 + 1/6 -4/5 + 1/9
¾ - 2/3 5/6 – 1/4

8. Mixed numbers Steps: 3 5/9 + 2 1/6 Convert to improper Find LCD
Solve/convert to mixed
3 5/ /6

9. St: Examples
4 7/10 + (-1 1/5)
-3 3/7 – 2 3/14

10. Variables
a/2 – a/6
5a/3 – a/6

11. ST: examples
4b/8 + b/12
10r/11 – r/8

12. Wrap-up
Questions/comments
Hw: workbook pg. 37