Add 80/21 and 70/20
1st number: 3 17/21, 2nd number: 3 10/20
80/21 + 70/20 is 307/42.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 21 × 20 = 420,
80/21 = 80 × 20/21 × 20 = 1600/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
70/20 = 70 × 21/20 × 21 = 1470/420 - Add the two like fractions:
1600/420 + 1470/420 = 1600 + 1470/420 = 3070/420 - 3070/420 simplified gives 307/42
- So, 80/21 + 70/20 = 307/42
In mixed form: 713/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 80/42+70/20 80/21+70/40 80/63+70/20 80/21+70/60