Add and Subtract Fractions by Decomposing

If you are asked to add fractions with unlike denominators, what do you have to do first?

• cross multiply

• add just the numerators

• find their common denominator

• just add both the numerators and denominators

Landon has 8/10 of his lawn left to mow. He mows 6/10 of the lawn before breaking for breakfast. How much more of the lawn does Landon have left to mow?

Kirk has 3/4 of a carton of eggs. He uses some of the eggs to make an omelette and now has 2/4 of the carton left. What fraction of the carton did Kirk use?

2/5 + 3/10

• 7/10

• 5/10

• 1/2

• 5/15

8/9 - 1/3 = 

• 7/6

• 5/9

• 2/3

• 8/27

1/3 + 5/12

• 6/12

• 6/15

• 3/4

• 4/4

1/4 + 5/8

• 6/8

• 6/12

• 7/8

• 8/8

7/10 - 1/2 = _____
in simplest form

• 2/10

• 1/5

• 6/10

• 8/2

Sally is painting her house. She used 1/8 of a gallon of paint in her bathroom, and 2/6 of a gallon of paint in her bedroom. How much paint did she use in all?

• 11/24

• 3/14

• 3/24

• 11/14

Tim has a board that is 5/6 feet long. He painted 2/18 feet of his board last night. How much more does Tim have left to paint?

• 13/18

• 7/24

• 7/18

• 3/7