Subtract 8/20 from 9/42
9/42 - 8/20 is -13/70.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 42 × 10 = 420,
9/42 = 9 × 10/42 × 10 = 90/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
8/20 = 8 × 21/20 × 21 = 168/420 - Subtract the two like fractions:
90/420 - 168/420 = 90 - 168/420 = -78/420 - After reducing the fraction, the answer is -13/70
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