Add 15/30 and 25/21
1st number: 15/30, 2nd number: 1 4/21
15/30 + 25/21 is 71/42.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 21 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 30 × 7 = 210,
15/30 = 15 × 7/30 × 7 = 105/210 - Likewise, for the 2nd fraction, since 21 × 10 = 210,
25/21 = 25 × 10/21 × 10 = 250/210 - Add the two like fractions:
105/210 + 250/210 = 105 + 250/210 = 355/210 - 355/210 simplified gives 71/42
- So, 15/30 + 25/21 = 71/42
In mixed form: 129/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 15/30+50/21 15/60+25/21 15/30+25/42 45/30+25/21 15/30+75/21 15/90+25/21 15/30+25/63 75/30+25/21