Add 15/30 and 21/90
15/30 + 21/90 is 11/15.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 90 is 90
Next, find the equivalent fraction of both fractional numbers with denominator 90 - For the 1st fraction, since 30 × 3 = 90,
15/30 = 15 × 3/30 × 3 = 45/90 - Likewise, for the 2nd fraction, since 90 × 1 = 90,
21/90 = 21 × 1/90 × 1 = 21/90 - Add the two like fractions:
45/90 + 21/90 = 45 + 21/90 = 66/90 - 66/90 simplified gives 11/15
- So, 15/30 + 21/90 = 11/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 15/30+42/90 15/60+21/90 45/30+21/90 15/30+63/90 15/90+21/90 75/30+21/90