Add 70/21 and 21/80, Solve 3 7/21 + 21/80 as a fraction

Add 70/21 and 21/80

1^st number: 3 7/21, 2^nd number: 21/80

70/21 + 21/80 is 863/240.

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,
70/21 = 70 × 80/21 × 80 = 5600/1680
Likewise, for the 2nd fraction, since 80 × 21 = 1680,
21/80 = 21 × 21/80 × 21 = 441/1680
Add the two like fractions:
5600/1680 + 441/1680 = 5600 + 441/1680 = 6041/1680
6041/1680 simplified gives 863/240
So, 70/21 + 21/80 = 863/240
In mixed form: 3143/240

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