Answers

Subtract 90/21 from 63/40

1^st number: 1 23/40, 2^nd number: 4 6/21

63/40 - 90/21 is -759/280.

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,
   63/40 = 63 × 21/40 × 21 = 1323/840
3. Likewise, for the 2nd fraction, since 21 × 40 = 840,
   90/21 = 90 × 40/21 × 40 = 3600/840
4. Subtract the two like fractions:
   1323/840 - 3600/840 = 1323 - 3600/840 = -2277/840
5. After reducing the fraction, the answer is -759/280

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