Subtracting Fractions

Show your work for each problem.

1.
What is ?
1. a)
2. b)
3. c)
4. d)
Answer:
With same denominators, subtract numerators: . Keep the denominator: . Never subtract denominators!
2.
Calculate and give your answer as a fraction.
Answer: 3/9
. Note: This can be simplified to , but is also correct.
3.
What is ?
1. a)
2. b)
3. c)
4. d)
Answer:
(simplified by dividing both by 6).
4.
Subtract:
Answer: 3/5
1. Are the denominators the same? yes
2. Subtract the numerators: 9 - 3 = ? 6
3. Write the result with denominator 10 6/10
4. Simplify by dividing both by GCF (2) 3/5
5.
What is the LCD (Least Common Denominator) of and ?
1. a)6
2. b)12
3. c)10
4. d)24
Answer: 12
Multiples of 4: 4, 8, 12... Multiples of 6: 6, 12... The LCD is 12 (smallest number divisible by both 4 and 6).
6.
Calculate . Give your answer in simplest form.
Answer: 1/4
LCD of 4 and 2 is 4. . So .
7.
Calculate
Answer: 7/12
1. What is the LCD of 6 and 4? 12
2. Convert to twelfths: = ? 10/12
3. Convert to twelfths: = ? 3/12
4. Subtract: = ? 7/12
8.
What is ?
1. a)
2. b)
3. c)
4. d)
Answer:
LCD = 12. , . So .
9.
Calculate . Give your answer in simplest form.
Answer: 3/10
LCD = 10. . So (already simplified).
10.
A recipe calls for cup of sugar. You want to use cup less. How much sugar will you use?
Answer: 5/12
1. What operation do you need? subtraction
2. What is the LCD of 4 and 3? 12
3. Convert to twelfths 9/12
4. Convert to twelfths 4/12
5. Calculate 5/12
11.
Calculate
Answer: 7/15
1. What is the LCD of 5 and 3? 15
2. Convert to fifteenths 12/15
3. Convert to fifteenths 5/15
4. Subtract: 7/15
12.
Calculate . Give your answer in simplest form.
Answer: 11/18
LCD = 18. , . So (already simplified).
13.
What is ?
1. a)
2. b)
3. c)
4. d)
Answer:
LCD = 24. , . So .
14.
You had of a pizza. You ate of the original pizza. How much pizza is left?
Answer: 11/24
1. What is the LCD of 6 and 8? 24
2. Convert to 24ths 20/24
3. Convert to 24ths 9/24
4. Subtract: 11/24
15.
Calculate . Give your answer in simplest form.
Answer: 13/24
LCD = 24. , . So (already simplified).
16.
Simplify:
Answer: 13/36
1. What is the LCD of 9 and 12? 36
2. Convert to 36ths 28/36
3. Convert to 36ths 15/36
4. Subtract: 13/36