Subtract 9/21 from 7/42
7/42 - 9/21 is -11/42.
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,
7/42 = 7 × 1/42 × 1 = 7/42 - Likewise, for the 2nd fraction, since 21 × 2 = 42,
9/21 = 9 × 2/21 × 2 = 18/42 - Subtract the two like fractions:
7/42 - 18/42 = 7 - 18/42 = -11/42
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