Add 7/21 and 28/9, Solve 7/21 + 3 1/9 as a fraction

Add 7/21 and 28/9

1^st number: 7/21, 2^nd number: 3 1/9

7/21 + 28/9 is 31/9.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 9 is 63

Next, find the equivalent fraction of both fractional numbers with denominator 63
For the 1st fraction, since 21 × 3 = 63,
7/21 = 7 × 3/21 × 3 = 21/63
Likewise, for the 2nd fraction, since 9 × 7 = 63,
28/9 = 28 × 7/9 × 7 = 196/63
Add the two like fractions:
21/63 + 196/63 = 21 + 196/63 = 217/63
217/63 simplified gives 31/9
So, 7/21 + 28/9 = 31/9
In mixed form: 34/9

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad