Add 84/20 and 28/21, Solve 4 4/20 + 1 7/21 as a fraction

Add 84/20 and 28/21

1^st number: 4 4/20, 2^nd number: 1 7/21

84/20 + 28/21 is 83/15.

Find the least common denominator or LCM of the two denominators:
LCM of 20 and 21 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 20 × 21 = 420,
84/20 = 84 × 21/20 × 21 = 1764/420
Likewise, for the 2nd fraction, since 21 × 20 = 420,
28/21 = 28 × 20/21 × 20 = 560/420
Add the two like fractions:
1764/420 + 560/420 = 1764 + 560/420 = 2324/420
2324/420 simplified gives 83/15
So, 84/20 + 28/21 = 83/15
In mixed form: 58/15

MathStep (Works offline)

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