Subtract 20/12 from 18/21
1st number: 18/21, 2nd number: 1 8/12
18/21 - 20/12 is -17/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 12 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 21 × 4 = 84,
18/21 = 18 × 4/21 × 4 = 72/84 - Likewise, for the 2nd fraction, since 12 × 7 = 84,
20/12 = 20 × 7/12 × 7 = 140/84 - Subtract the two like fractions:
72/84 - 140/84 = 72 - 140/84 = -68/84 - After reducing the fraction, the answer is -17/21
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