Subtract 42/70 from 21/40
21/40 - 42/70 is -3/40.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 70 is 280
Next, find the equivalent fraction of both fractional numbers with denominator 280 - For the 1st fraction, since 40 × 7 = 280,
21/40 = 21 × 7/40 × 7 = 147/280 - Likewise, for the 2nd fraction, since 70 × 4 = 280,
42/70 = 42 × 4/70 × 4 = 168/280 - Subtract the two like fractions:
147/280 - 168/280 = 147 - 168/280 = -21/280 - After reducing the fraction, the answer is -3/40
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