Title: Lesson 6-4
Author: mark_cameron
Last saved by: MHE
Company: McGraw-Hill

Lesson 3-9

For Examples 6-7 Subtract Fractions with Unlike Denominators
a. Find  −  using a model. 

	

	−  

b. Find  −  using the LCD. 
 List multiples of each denominator.
5: 5, 10, 15, 20
4: 4, 8, 12, 16, 20

The least common denominator of  and  is 20.

Write the problem.	Rename using the LCD, 20.	Subtract the fractions.
	 	→ 	 	=	 	→ 	

	−   	→ 	−   	= 	−  	→ 	−