Add 8/40 and 30/21, Solve 8/40 + 1 9/21 as a fraction

Add 8/40 and 30/21

1^st number: 8/40, 2^nd number: 1 9/21

8/40 + 30/21 is 57/35.

Find the least common denominator or LCM of the two denominators:
LCM of 40 and 21 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 40 × 21 = 840,
8/40 = 8 × 21/40 × 21 = 168/840
Likewise, for the 2nd fraction, since 21 × 40 = 840,
30/21 = 30 × 40/21 × 40 = 1200/840
Add the two like fractions:
168/840 + 1200/840 = 168 + 1200/840 = 1368/840
1368/840 simplified gives 57/35
So, 8/40 + 30/21 = 57/35
In mixed form: 122/35

MathStep (Works offline)

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