Subtract 15/21 from 15/40
15/40 - 15/21 is -19/56.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 21 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 40 × 21 = 840,
15/40 = 15 × 21/40 × 21 = 315/840 - Likewise, for the 2nd fraction, since 21 × 40 = 840,
15/21 = 15 × 40/21 × 40 = 600/840 - Subtract the two like fractions:
315/840 - 600/840 = 315 - 600/840 = -285/840 - After reducing the fraction, the answer is -19/56
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