Add 75/20 and 21/84, Solve 3 15/20 + 21/84 as a fraction

Add 75/20 and 21/84

1^st number: 3 15/20, 2^nd number: 21/84

75/20 + 21/84 is 4/1.

Find the least common denominator or LCM of the two denominators:
LCM of 20 and 84 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 20 × 21 = 420,
75/20 = 75 × 21/20 × 21 = 1575/420
Likewise, for the 2nd fraction, since 84 × 5 = 420,
21/84 = 21 × 5/84 × 5 = 105/420
Add the two like fractions:
1575/420 + 105/420 = 1575 + 105/420 = 1680/420
1680/420 simplified gives 4/1
So, 75/20 + 21/84 = 4/1

MathStep (Works offline)

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