Add 7/21 and 20/45
7/21 + 20/45 is 7/9.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 45 is 315
Next, find the equivalent fraction of both fractional numbers with denominator 315 - For the 1st fraction, since 21 × 15 = 315,
7/21 = 7 × 15/21 × 15 = 105/315 - Likewise, for the 2nd fraction, since 45 × 7 = 315,
20/45 = 20 × 7/45 × 7 = 140/315 - Add the two like fractions:
105/315 + 140/315 = 105 + 140/315 = 245/315 - 245/315 simplified gives 7/9
- So, 7/21 + 20/45 = 7/9
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/21+20/45 7/21+40/45 7/42+20/45 7/21+20/90 7/21+60/45 7/63+20/45 35/21+20/45 49/21+20/45