Add 20/15 and 3/21
1st number: 1 5/15, 2nd number: 3/21
20/15 + 3/21 is 31/21.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 15 and 21 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 15 × 7 = 105,
20/15 = 20 × 7/15 × 7 = 140/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
3/21 = 3 × 5/21 × 5 = 15/105 - Add the two like fractions:
140/105 + 15/105 = 140 + 15/105 = 155/105 - 155/105 simplified gives 31/21
- So, 20/15 + 3/21 = 31/21
In mixed form: 110/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/15+3/21 20/15+6/21 20/30+3/21 20/15+3/42 60/15+3/21 20/15+9/21 20/45+3/21 20/15+3/63 20/15+15/21 20/75+3/21