Adding & Subtracting Fractions — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 512 + 412 = 912.
Both fractions have 12 as the denominator, so add the numerators: 5 + 4 = 9, giving 912.
2. 79 − 29 = 59.
With like denominators (9), subtract the numerators: 7 − 2 = 5, so the answer is 59.
3. 310 + 610 = 910.
The denominator stays 10 because these are like fractions, and 3 + 6 = 9, making the sum 910.
4. 811 − 311 = 511.
Since both fractions are elevenths, only the numerators change: 8 − 3 = 5, so you get 511.
5. 27 + 47 = 67.
Keep the denominator 7 and add the numerators: 2 + 4 = 6, which gives 67.
6. 68 − 28 = 48.
Both fractions are eighths, so subtract the tops: 6 − 2 = 4, and the answer is 48.
7. 16 + 36 = 46.
With the same denominator of 6, add the numerators: 1 + 3 = 4, so the sum is 46.
8. 1012 − 612 = 412.
Subtract just the numerators because the denominators match: 10 − 6 = 4, giving 412.
9. 35 + 15 = 45.
Both fractions are fifths, so the denominator stays 5 and 3 + 1 = 4, making the answer 45.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
46 + 26
→ 66
68
910 − 510
→ 410
33
13 + 23
→ 33
410
78 − 18
→ 68
66
For each pair, add or subtract only the numerators while keeping the denominator: 4+2=6 over 6, 9−5=4 over 10, 1+2=3 over 3, and 7−1=6 over 8.