Add 81/21 and 54/42, Solve 3 18/21 + 1 12/42 as a fraction

Add 81/21 and 54/42

1^st number: 3 18/21, 2^nd number: 1 12/42

81/21 + 54/42 is 36/7.

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

Next, find the equivalent fraction of both fractional numbers with denominator 42
For the 1st fraction, since 21 × 2 = 42,
81/21 = 81 × 2/21 × 2 = 162/42
Likewise, for the 2nd fraction, since 42 × 1 = 42,
54/42 = 54 × 1/42 × 1 = 54/42
Add the two like fractions:
162/42 + 54/42 = 162 + 54/42 = 216/42
216/42 simplified gives 36/7
So, 81/21 + 54/42 = 36/7
In mixed form: 51/7

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