Add 20/15 and 2/21, Solve 1 5/15 + 2/21 as a fraction

Add 20/15 and 2/21

1^st number: 1 5/15, 2^nd number: 2/21

20/15 + 2/21 is 10/7.

Find the least common denominator or LCM of the two denominators:
LCM of 15 and 21 is 105

Next, find the equivalent fraction of both fractional numbers with denominator 105
For the 1st fraction, since 15 × 7 = 105,
20/15 = 20 × 7/15 × 7 = 140/105
Likewise, for the 2nd fraction, since 21 × 5 = 105,
2/21 = 2 × 5/21 × 5 = 10/105
Add the two like fractions:
140/105 + 10/105 = 140 + 10/105 = 150/105
150/105 simplified gives 10/7
So, 20/15 + 2/21 = 10/7
In mixed form: 13/7

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad