Subtract 8/21 from 7/40
7/40 - 8/21 is -173/840.
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,
7/40 = 7 × 21/40 × 21 = 147/840 - Likewise, for the 2nd fraction, since 21 × 40 = 840,
8/21 = 8 × 40/21 × 40 = 320/840 - Subtract the two like fractions:
147/840 - 320/840 = 147 - 320/840 = -173/840
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