Answers

Subtract 63/21 from 18/40

1^st number: 18/40, 2^nd number: 3 0/21

18/40 - 63/21 is -51/20.

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,
   18/40 = 18 × 21/40 × 21 = 378/840
3. Likewise, for the 2nd fraction, since 21 × 40 = 840,
   63/21 = 63 × 40/21 × 40 = 2520/840
4. Subtract the two like fractions:
   378/840 - 2520/840 = 378 - 2520/840 = -2142/840
5. After reducing the fraction, the answer is -51/20

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