Add 80/21 and 21/80, Solve 3 17/21 + 21/80 as a fraction

Add 80/21 and 21/80

1^st number: 3 17/21, 2^nd number: 21/80

80/21 + 21/80 is 6841/1680.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 80 is 1680

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 21 × 80 = 1680,
80/21 = 80 × 80/21 × 80 = 6400/1680
Likewise, for the 2nd fraction, since 80 × 21 = 1680,
21/80 = 21 × 21/80 × 21 = 441/1680
Add the two like fractions:
6400/1680 + 441/1680 = 6400 + 441/1680 = 6841/1680
So, 80/21 + 21/80 = 6841/1680
In mixed form: 4121/1680

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