Add 30/54 and 80/21, Solve 30/54 + 3 17/21 as a fraction

Add 30/54 and 80/21

1^st number: 30/54, 2^nd number: 3 17/21

30/54 + 80/21 is 275/63.

Find the least common denominator or LCM of the two denominators:
LCM of 54 and 21 is 378

Next, find the equivalent fraction of both fractional numbers with denominator 378
For the 1st fraction, since 54 × 7 = 378,
30/54 = 30 × 7/54 × 7 = 210/378
Likewise, for the 2nd fraction, since 21 × 18 = 378,
80/21 = 80 × 18/21 × 18 = 1440/378
Add the two like fractions:
210/378 + 1440/378 = 210 + 1440/378 = 1650/378
1650/378 simplified gives 275/63
So, 30/54 + 80/21 = 275/63
In mixed form: 423/63

MathStep (Works offline)

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