Answers

Subtract 40/8 from 21/81

1^st number: 21/81, 2^nd number: 5 0/8

21/81 - 40/8 is -128/27.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 81 and 8 is 648
   
   Next, find the equivalent fraction of both fractional numbers with denominator 648
2. For the 1st fraction, since 81 × 8 = 648,
   21/81 = 21 × 8/81 × 8 = 168/648
3. Likewise, for the 2nd fraction, since 8 × 81 = 648,
   40/8 = 40 × 81/8 × 81 = 3240/648
4. Subtract the two like fractions:
   168/648 - 3240/648 = 168 - 3240/648 = -3072/648
5. After reducing the fraction, the answer is -128/27

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