Add 15/5 and 72/21
1st number: 3 0/5, 2nd number: 3 9/21
15/5 + 72/21 is 45/7.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 5 and 21 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 5 × 21 = 105,
15/5 = 15 × 21/5 × 21 = 315/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
72/21 = 72 × 5/21 × 5 = 360/105 - Add the two like fractions:
315/105 + 360/105 = 315 + 360/105 = 675/105 - 675/105 simplified gives 45/7
- So, 15/5 + 72/21 = 45/7
In mixed form: 63/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/5+72/21 15/10+72/21 15/5+72/42 45/5+72/21 15/5+72/63 75/5+72/21 15/25+72/21 15/35+72/21