Add 8/20 and 7/21
8/20 + 7/21 is 11/15.
Steps for adding fractions
- 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,
8/20 = 8 × 21/20 × 21 = 168/420 - Likewise, for the 2nd fraction, since 21 × 20 = 420,
7/21 = 7 × 20/21 × 20 = 140/420 - Add the two like fractions:
168/420 + 140/420 = 168 + 140/420 = 308/420 - 308/420 simplified gives 11/15
- So, 8/20 + 7/21 = 11/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/20+7/21 8/20+14/21 8/40+7/21 8/20+7/42 24/20+7/21 8/60+7/21 8/20+7/63 40/20+7/21 8/20+35/21 56/20+7/21 8/20+49/21