Subtract 20/21 from 1/2
1/2 - 20/21 is -19/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 2 and 21 is 42
Next, find the equivalent fraction of both fractional numbers with denominator 42 - For the 1st fraction, since 2 × 21 = 42,
1/2 = 1 × 21/2 × 21 = 21/42 - Likewise, for the 2nd fraction, since 21 × 2 = 42,
20/21 = 20 × 2/21 × 2 = 40/42 - Subtract the two like fractions:
21/42 - 40/42 = 21 - 40/42 = -19/42
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