Subtract 20/40 from 15/42
15/42 - 20/40 is -1/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 40 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 42 × 20 = 840,
15/42 = 15 × 20/42 × 20 = 300/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
20/40 = 20 × 21/40 × 21 = 420/840 - Subtract the two like fractions:
300/840 - 420/840 = 300 - 420/840 = -120/840 - After reducing the fraction, the answer is -1/7
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