Add 21/28 and 15/20
21/28 + 15/20 is 3/2.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 28 and 20 is 140
Next, find the equivalent fraction of both fractional numbers with denominator 140 - For the 1st fraction, since 28 × 5 = 140,
21/28 = 21 × 5/28 × 5 = 105/140 - Likewise, for the 2nd fraction, since 20 × 7 = 140,
15/20 = 15 × 7/20 × 7 = 105/140 - Add the two like fractions:
105/140 + 105/140 = 105 + 105/140 = 210/140 - 210/140 simplified gives 3/2
- So, 21/28 + 15/20 = 3/2
In mixed form: 11/2
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/28+15/20 21/28+30/20 21/56+15/20 21/28+15/40 63/28+15/20 21/28+45/20 21/84+15/20 21/28+15/60 21/28+75/20