Add 4/15 and 20/21
4/15 + 20/21 is 128/105.
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,
4/15 = 4 × 7/15 × 7 = 28/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
20/21 = 20 × 5/21 × 5 = 100/105 - Add the two like fractions:
28/105 + 100/105 = 28 + 100/105 = 128/105 - So, 4/15 + 20/21 = 128/105
In mixed form: 123/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 8/15+20/21 4/15+40/21 4/30+20/21 4/15+20/42 12/15+20/21 4/15+60/21 4/45+20/21 4/15+20/63 20/15+20/21 4/75+20/21 28/15+20/21