Add 21/45 and 12/30
21/45 + 12/30 is 13/15.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 45 and 30 is 90
Next, find the equivalent fraction of both fractional numbers with denominator 90 - For the 1st fraction, since 45 × 2 = 90,
21/45 = 21 × 2/45 × 2 = 42/90 - Likewise, for the 2nd fraction, since 30 × 3 = 90,
12/30 = 12 × 3/30 × 3 = 36/90 - Add the two like fractions:
42/90 + 36/90 = 42 + 36/90 = 78/90 - 78/90 simplified gives 13/15
- So, 21/45 + 12/30 = 13/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/45+12/30 21/45+24/30 21/90+12/30 21/45+12/60 63/45+12/30 21/45+36/30 21/45+12/90 21/45+60/30 21/45+84/30