Add 21/28 and 18/80
21/28 + 18/80 is 39/40.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 28 and 80 is 560
Next, find the equivalent fraction of both fractional numbers with denominator 560 - For the 1st fraction, since 28 × 20 = 560,
21/28 = 21 × 20/28 × 20 = 420/560 - Likewise, for the 2nd fraction, since 80 × 7 = 560,
18/80 = 18 × 7/80 × 7 = 126/560 - Add the two like fractions:
420/560 + 126/560 = 420 + 126/560 = 546/560 - 546/560 simplified gives 39/40
- So, 21/28 + 18/80 = 39/40
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/28+18/80 21/28+36/80 21/56+18/80 63/28+18/80 21/28+54/80 21/84+18/80 21/28+90/80