Adding and Subtracting with Fractions SWBAT ADD AND SUBTRACT FRACTIONS USING A COMMON DENOMINATOR.

1. There are 65 boys and 52 girls in the drama club. What is the ratio of boys to girls in simplest form? a. 15: 2 b. 15: 5 c. 5: 4 d. 20: The formula for the perimeter of a square is 4s, where s is the length of one side. If s = ½ what is the perimeter of the square? a. 3 b. 9 c. 4 d If n = 6, evaluate the expression 24 ÷ 2n = a. 9 b. 12 c. 2 d The following table shows the number of eggs a chicken laid over the course of 5 months. In which months did the chicken lay between 35 and 45 eggs? a. December b. February c. March d. April MonthNumber of Eggs December22 January19 February40 March48 April34

Adding Fractions  Brainstorm  Can you add 1/3 + ¼?

Adding Fractions  Brainstorm  Can you add 1/3 + ¼? What if we found a common denominator?

Adding Fractions Adding 1/3 + ¼ using a common denominator: 12 1/3 = 4/12 ¼ = 3/12 We can add the numerators together once we have a common denominator. 4/12 + 3/12 = 7/12

Now you try… 1/5 + ¾ = Rewrite using a common denominator: ?/20 + ?/20 = ?/20 Solution:

Now you try… 2/9 + 2/3 Rewrite with common denominator: Solution:

Practice on your own  Find a common denominator, then add the fractions. Record your work and answers in your notebook. 1. 2/7 + 1/3 2. 9/10 + 2/15 3. ¼ + 3/8 4. 2/6 + 3/4

Subtracting Fractions  We follow the same rule as addition—we must find a common denominator then subtract the numerators. Ex: 4/5 - 2/3 Common Denominator? 15 12/15 – 10/15 = 2/15

Subtracting Fractions ¾ - ½ Common Denominator: 4 ¾ - 2/4 = 1/4

Practice 1. 2/7 + 2/3 2. 4/5 + 3/7 3. 3/8 – ¼ 4. ¾ - 2/6

Exit Ticket 1. 5/9 + 2/6 2. 9/10 + ¾ 3. 7/8 – 2/3