Add 25/15 and 1/21, Solve 1 10/15 + 1/21 as a fraction

Add 25/15 and 1/21

1^st number: 1 10/15, 2^nd number: 1/21

25/15 + 1/21 is 12/7.

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,
25/15 = 25 × 7/15 × 7 = 175/105
Likewise, for the 2nd fraction, since 21 × 5 = 105,
1/21 = 1 × 5/21 × 5 = 5/105
Add the two like fractions:
175/105 + 5/105 = 175 + 5/105 = 180/105
180/105 simplified gives 12/7
So, 25/15 + 1/21 = 12/7
In mixed form: 15/7

MathStep (Works offline)

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