Let’s solve each problem step by step. We’re adding fractions with different denominators, so we need to find a common denominator first — usually the least common multiple (LCM) of the two denominators. Then convert both fractions to have that denominator, add the numerators, and simplify if needed.
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1) 2/5 + 5/10
→ LCM of 5 and 10 is 10
→ 2/5 = 4/10
→ 4/10 + 5/10 = 9/10
✔ Answer: 9/10
2) 4/9 + 3/12
→ Simplify 3/12 → 1/4
→ LCM of 9 and 4 is 36
→ 4/9 = 16/36; 1/4 = 9/36
→ 16/36 + 9/36 = 25/36
✔ Answer: 25/36
3) 1/4 + 3/5
→ LCM of 4 and 5 is 20
→ 1/4 = 5/20; 3/5 = 12/20
→ 5/20 + 12/20 = 17/20
✔ Answer: 17/20
4) 2/5 + 1/3
→ LCM of 5 and 3 is 15
→ 2/5 = 6/15; 1/3 = 5/15
→ 6/15 + 5/15 = 11/15
✔ Answer: 11/15
5) 2/5 + 3/10
→ LCM of 5 and 10 is 10
→ 2/5 = 4/10
→ 4/10 + 3/10 = 7/10
✔ Answer: 7/10
6) 5/14 + 3/7
→ LCM of 14 and 7 is 14
→ 3/7 = 6/14
→ 5/14 + 6/14 = 11/14
✔ Answer: 11/14
7) 5/9 + 1/3
→ LCM of 9 and 3 is 9
→ 1/3 = 3/9
→ 5/9 + 3/9 = 8/9
✔ Answer: 8/9
8) 1/6 + 2/9
→ LCM of 6 and 9 is 18
→ 1/6 = 3/18; 2/9 = 4/18
→ 3/18 + 4/18 = 7/18
✔ Answer: 7/18
9) 5/15 + 3/5
→ Simplify 5/15 → 1/3
→ LCM of 3 and 5 is 15
→ 1/3 = 5/15; 3/5 = 9/15
→ 5/15 + 9/15 = 14/15
✔ Answer: 14/15
10) 3/9 + 1/5
→ Simplify 3/9 → 1/3
→ LCM of 3 and 5 is 15
→ 1/3 = 5/15; 1/5 = 3/15
→ 5/15 + 3/15 = 8/15
✔ Answer: 8/15
11) 4/10 + 7/20
→ Simplify 4/10 → 2/5
→ LCM of 5 and 20 is 20
→ 2/5 = 8/20
→ 8/20 + 7/20 = 15/20 → simplify → 3/4
✔ Answer: 3/4
12) 3/10 + 2/15
→ LCM of 10 and 15 is 30
→ 3/10 = 9/30; 2/15 = 4/30
→ 9/30 + 4/30 = 13/30
✔ Answer: 13/30
13) 6/15 + 3/20
→ Simplify 6/15 → 2/5
→ LCM of 5 and 20 is 20
→ 2/5 = 8/20
→ 8/20 + 3/20 = 11/20
✔ Answer: 11/20
14) 1/4 + 4/10
→ Simplify 4/10 → 2/5
→ LCM of 4 and 5 is 20
→ 1/4 = 5/20; 2/5 = 8/20
→ 5/20 + 8/20 = 13/20
✔ Answer: 13/20
15) 3/15 + 7/12
→ Simplify 3/15 → 1/5
→ LCM of 5 and 12 is 60
→ 1/5 = 12/60; 7/12 = 35/60
→ 12/60 + 35/60 = 47/60
✔ Answer: 47/60
16) 4/15 + 3/25
→ LCM of 15 and 25 is 75
→ 4/15 = 20/75; 3/25 = 9/75
→ 20/75 + 9/75 = 29/75
✔ Answer: 29/75
17) 4/10 + 7/15
→ Simplify 4/10 → 2/5
→ LCM of 5 and 15 is 15
→ 2/5 = 6/15
→ 6/15 + 7/15 = 13/15
✔ Answer: 13/15
18) 3/10 + 2/15
→ LCM of 10 and 15 is 30
→ 3/10 = 9/30; 2/15 = 4/30
→ 9/30 + 4/30 = 13/30
✔ Answer: 13/30
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Final Answer:
1) 9/10
2) 25/36
3) 17/20
4) 11/15
5) 7/10
6) 11/14
7) 8/9
8) 7/18
9) 14/15
10) 8/15
11) 3/4
12) 13/30
13) 11/20
14) 13/20
15) 47/60
16) 29/75
17) 13/15
18) 13/30
Parent Tip: Review the logic above to help your child master the concept of adding and subtracting fractions with different denominators worksheet.
