Add 72/21 and 45/6, Solve 3 9/21 + 7 3/6 as a fraction

Add 72/21 and 45/6

1^st number: 3 9/21, 2^nd number: 7 3/6

72/21 + 45/6 is 153/14.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 6 is 42

Next, find the equivalent fraction of both fractional numbers with denominator 42
For the 1st fraction, since 21 × 2 = 42,
72/21 = 72 × 2/21 × 2 = 144/42
Likewise, for the 2nd fraction, since 6 × 7 = 42,
45/6 = 45 × 7/6 × 7 = 315/42
Add the two like fractions:
144/42 + 315/42 = 144 + 315/42 = 459/42
459/42 simplified gives 153/14
So, 72/21 + 45/6 = 153/14
In mixed form: 1013/14

MathStep (Works offline)

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