Answers

Subtract 21/40 from 4/81

4/81 - 21/40 is -1541/3240.

Steps for subtracting fractions

1. 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
2. For the 1st fraction, since 81 × 40 = 3240,
   4/81 = 4 × 40/81 × 40 = 160/3240
3. Likewise, for the 2nd fraction, since 40 × 81 = 3240,
   21/40 = 21 × 81/40 × 81 = 1701/3240
4. Subtract the two like fractions:
   160/3240 - 1701/3240 = 160 - 1701/3240 = -1541/3240

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