Add 21/18 and 54/21, Solve 1 3/18 + 2 12/21 as a fraction

Add 21/18 and 54/21

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

21/18 + 54/21 is 157/42.

Find the least common denominator or LCM of the two denominators:
LCM of 18 and 21 is 126

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 18 × 7 = 126,
21/18 = 21 × 7/18 × 7 = 147/126
Likewise, for the 2nd fraction, since 21 × 6 = 126,
54/21 = 54 × 6/21 × 6 = 324/126
Add the two like fractions:
147/126 + 324/126 = 147 + 324/126 = 471/126
471/126 simplified gives 157/42
So, 21/18 + 54/21 = 157/42
In mixed form: 331/42

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