Subtract 21/40 from 7/81
7/81 - 21/40 is -1421/3240.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 81 and 40 is 3240
Next, find the equivalent fraction of both fractional numbers with denominator 3240 - For the 1st fraction, since 81 × 40 = 3240,
7/81 = 7 × 40/81 × 40 = 280/3240 - Likewise, for the 2nd fraction, since 40 × 81 = 3240,
21/40 = 21 × 81/40 × 81 = 1701/3240 - Subtract the two like fractions:
280/3240 - 1701/3240 = 280 - 1701/3240 = -1421/3240
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