Add 7/21 and 35/9, Solve 7/21 + 3 8/9 as a fraction

Add 7/21 and 35/9

1^st number: 7/21, 2^nd number: 3 8/9

7/21 + 35/9 is 38/9.

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,
35/9 = 35 × 7/9 × 7 = 245/63
Add the two like fractions:
21/63 + 245/63 = 21 + 245/63 = 266/63
266/63 simplified gives 38/9
So, 7/21 + 35/9 = 38/9
In mixed form: 42/9

MathStep (Works offline)

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