Add 28/21 and 3/4, Solve 1 7/21 + 3/4 as a fraction

Add 28/21 and 3/4

1^st number: 1 7/21, 2^nd number: 3/4

28/21 + 3/4 is 25/12.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 4 is 84

Next, find the equivalent fraction of both fractional numbers with denominator 84
For the 1st fraction, since 21 × 4 = 84,
28/21 = 28 × 4/21 × 4 = 112/84
Likewise, for the 2nd fraction, since 4 × 21 = 84,
3/4 = 3 × 21/4 × 21 = 63/84
Add the two like fractions:
112/84 + 63/84 = 112 + 63/84 = 175/84
175/84 simplified gives 25/12
So, 28/21 + 3/4 = 25/12
In mixed form: 21/12

MathStep (Works offline)

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