Subtract 16/21 from 20/42
20/42 - 16/21 is -2/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 21 is 42
Next, find the equivalent fraction of both fractional numbers with denominator 42 - For the 1st fraction, since 42 × 1 = 42,
20/42 = 20 × 1/42 × 1 = 20/42 - Likewise, for the 2nd fraction, since 21 × 2 = 42,
16/21 = 16 × 2/21 × 2 = 32/42 - Subtract the two like fractions:
20/42 - 32/42 = 20 - 32/42 = -12/42 - After reducing the fraction, the answer is -2/7
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