Add 81/21 and 5/20, Solve 3 18/21 + 5/20 as a fraction

Add 81/21 and 5/20

1^st number: 3 18/21, 2^nd number: 5/20

81/21 + 5/20 is 115/28.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 21 × 20 = 420,
81/21 = 81 × 20/21 × 20 = 1620/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
5/20 = 5 × 21/20 × 21 = 105/420
Add the two like fractions:
1620/420 + 105/420 = 1620 + 105/420 = 1725/420
1725/420 simplified gives 115/28
So, 81/21 + 5/20 = 115/28
In mixed form: 43/28

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