Answers

Subtract 40/21 from 15/40

1^st number: 15/40, 2^nd number: 1 19/21

15/40 - 40/21 is -257/168.

Steps for subtracting fractions

1. 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
2. For the 1st fraction, since 40 × 21 = 840,
   15/40 = 15 × 21/40 × 21 = 315/840
3. Likewise, for the 2nd fraction, since 21 × 40 = 840,
   40/21 = 40 × 40/21 × 40 = 1600/840
4. Subtract the two like fractions:
   315/840 - 1600/840 = 315 - 1600/840 = -1285/840
5. After reducing the fraction, the answer is -257/168

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