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Math Grade 4-5 Answer Key

Adding and Subtracting Fractions

Practice finding sums and differences of fractions

Answer Key
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Adding and Subtracting Fractions

Practice finding sums and differences of fractions

Math - Grade 4-5

Instructions: Solve each fraction problem carefully. Simplify your answers when possible and show your work in the space provided.
  1. 1

    Add the fractions: 2/8 + 3/8

    When denominators are the same, keep the denominator and add the numerators.

    The sum is 5/8 because the denominators are the same, so you add the numerators: 2 + 3 = 5.
  2. 2

    Subtract the fractions: 7/10 - 4/10

    The difference is 3/10 because the denominators are the same, so you subtract the numerators: 7 - 4 = 3.
  3. 3

    Add the fractions: 1/6 + 4/6

    Look at the bottom numbers first.

    The sum is 5/6 because the denominators are the same, so you add the numerators: 1 + 4 = 5.
  4. 4

    Subtract the fractions: 9/12 - 5/12

    The difference is 4/12, which simplifies to 1/3. You subtract the numerators and then simplify the fraction.
  5. 5

    Add the fractions: 3/4 + 1/4

    Think about how many fourths make a whole.

    The sum is 4/4, which equals 1 whole. Four fourths make one whole.
  6. 6

    Subtract the fractions: 5/8 - 1/8

    The difference is 4/8, which simplifies to 1/2. You subtract the numerators and then simplify.
  7. 7

    Add the fractions: 1/2 + 1/4

    Change the fractions so they have the same denominator.

    The sum is 3/4. You can rename 1/2 as 2/4, and then 2/4 + 1/4 = 3/4.
  8. 8

    Subtract the fractions: 3/4 - 1/2

    The difference is 1/4. Rename 1/2 as 2/4, and then 3/4 - 2/4 = 1/4.
  9. 9

    Add the fractions: 2/3 + 1/6

    Find a common denominator that both 3 and 6 can use.

    The sum is 5/6. Rename 2/3 as 4/6, and then 4/6 + 1/6 = 5/6.
  10. 10

    Subtract the fractions: 5/6 - 1/3

    The difference is 3/6, which simplifies to 1/2. Rename 1/3 as 2/6, and then subtract.
  11. 11

    Lena ate 2/8 of a cake in the morning and 3/8 of the cake in the evening. What fraction of the cake did she eat in all?

    Add the parts she ate.

    Lena ate 5/8 of the cake in all because 2/8 + 3/8 = 5/8.
  12. 12

    A water tank was 6/10 full. Then 2/10 of the tank was used. What fraction of the tank is still full?

    The tank is 4/10 full, which simplifies to 2/5. You subtract 2/10 from 6/10.
  13. 13

    Noah walked 1/2 mile in the morning and 1/3 mile in the afternoon. How far did he walk altogether?

    Use sixths as the common denominator.

    Noah walked 5/6 mile altogether. Rename 1/2 as 3/6 and 1/3 as 2/6, then add 3/6 + 2/6 = 5/6.
  14. 14

    Mia had 7/8 yard of ribbon. She used 3/8 yard for a project. How much ribbon does she have left?

    Mia has 4/8 yard left, which simplifies to 1/2 yard. You subtract 3/8 from 7/8.
  15. 15

    A class completed 1/4 of a poster on Monday and 2/4 of the poster on Tuesday. What fraction of the poster is finished now?

    Add the fractions because both parts are completed.

    The class has finished 3/4 of the poster because 1/4 + 2/4 = 3/4.
LivePhysics.com Math - Grade 4-5 - Answer Key