Add 15/20 and 81/21
1st number: 15/20, 2nd number: 3 18/21
15/20 + 81/21 is 129/28.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 20 and 21 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 20 × 21 = 420,
15/20 = 15 × 21/20 × 21 = 315/420 - Likewise, for the 2nd fraction, since 21 × 20 = 420,
81/21 = 81 × 20/21 × 20 = 1620/420 - Add the two like fractions:
315/420 + 1620/420 = 315 + 1620/420 = 1935/420 - 1935/420 simplified gives 129/28
- So, 15/20 + 81/21 = 129/28
In mixed form: 417/28
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