Add 90/12 and 15/21
1st number: 7 6/12, 2nd number: 15/21
90/12 + 15/21 is 115/14.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 12 and 21 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 12 × 7 = 84,
90/12 = 90 × 7/12 × 7 = 630/84 - Likewise, for the 2nd fraction, since 21 × 4 = 84,
15/21 = 15 × 4/21 × 4 = 60/84 - Add the two like fractions:
630/84 + 60/84 = 630 + 60/84 = 690/84 - 690/84 simplified gives 115/14
- So, 90/12 + 15/21 = 115/14
In mixed form: 83/14
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 90/12+30/21 90/24+15/21 90/12+15/42 90/12+45/21 90/36+15/21 90/12+15/63 90/12+75/21 90/60+15/21 90/84+15/21