Add 54/21 and 81/42, Solve 2 12/21 + 1 39/42 as a fraction

Add 54/21 and 81/42

1^st number: 2 12/21, 2^nd number: 1 39/42

54/21 + 81/42 is 9/2.

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,
54/21 = 54 × 2/21 × 2 = 108/42
Likewise, for the 2nd fraction, since 42 × 1 = 42,
81/42 = 81 × 1/42 × 1 = 81/42
Add the two like fractions:
108/42 + 81/42 = 108 + 81/42 = 189/42
189/42 simplified gives 9/2
So, 54/21 + 81/42 = 9/2
In mixed form: 41/2

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