Add 12/8 and 28/21, Solve 1 4/8 + 1 7/21 as a fraction

Add 12/8 and 28/21

1^st number: 1 4/8, 2^nd number: 1 7/21

12/8 + 28/21 is 17/6.

Find the least common denominator or LCM of the two denominators:
LCM of 8 and 21 is 168

Next, find the equivalent fraction of both fractional numbers with denominator 168
For the 1st fraction, since 8 × 21 = 168,
12/8 = 12 × 21/8 × 21 = 252/168
Likewise, for the 2nd fraction, since 21 × 8 = 168,
28/21 = 28 × 8/21 × 8 = 224/168
Add the two like fractions:
252/168 + 224/168 = 252 + 224/168 = 476/168
476/168 simplified gives 17/6
So, 12/8 + 28/21 = 17/6
In mixed form: 25/6

MathStep (Works offline)

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