Add 28/21 and 72/20
1st number: 1 7/21, 2nd number: 3 12/20
28/21 + 72/20 is 74/15.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 21 × 20 = 420,
28/21 = 28 × 20/21 × 20 = 560/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
72/20 = 72 × 21/20 × 21 = 1512/420 - Add the two like fractions:
560/420 + 1512/420 = 560 + 1512/420 = 2072/420 - 2072/420 simplified gives 74/15
- So, 28/21 + 72/20 = 74/15
In mixed form: 414/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 56/21+72/20 28/42+72/20 28/21+72/40 84/21+72/20 28/63+72/20 28/21+72/60