Add 20/15 and 70/21
1st number: 1 5/15, 2nd number: 3 7/21
20/15 + 70/21 is 14/3.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 15 and 21 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 15 × 7 = 105,
20/15 = 20 × 7/15 × 7 = 140/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
70/21 = 70 × 5/21 × 5 = 350/105 - Add the two like fractions:
140/105 + 350/105 = 140 + 350/105 = 490/105 - 490/105 simplified gives 14/3
- So, 20/15 + 70/21 = 14/3
In mixed form: 42/3
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/15+70/21 20/30+70/21 20/15+70/42 60/15+70/21 20/45+70/21 20/15+70/63 20/75+70/21