Add 15/21 and 30/70
15/21 + 30/70 is 8/7.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 70 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 21 × 10 = 210,
15/21 = 15 × 10/21 × 10 = 150/210 - Likewise, for the 2nd fraction, since 70 × 3 = 210,
30/70 = 30 × 3/70 × 3 = 90/210 - Add the two like fractions:
150/210 + 90/210 = 150 + 90/210 = 240/210 - 240/210 simplified gives 8/7
- So, 15/21 + 30/70 = 8/7
In mixed form: 11/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/21+30/70 15/21+60/70 15/42+30/70 45/21+30/70 15/21+90/70 15/63+30/70 75/21+30/70