Answers

Subtract 70/21 from 20/72

1^st number: 20/72, 2^nd number: 3 7/21

20/72 - 70/21 is -55/18.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 72 and 21 is 504
   
   Next, find the equivalent fraction of both fractional numbers with denominator 504
2. For the 1st fraction, since 72 × 7 = 504,
   20/72 = 20 × 7/72 × 7 = 140/504
3. Likewise, for the 2nd fraction, since 21 × 24 = 504,
   70/21 = 70 × 24/21 × 24 = 1680/504
4. Subtract the two like fractions:
   140/504 - 1680/504 = 140 - 1680/504 = -1540/504
5. After reducing the fraction, the answer is -55/18

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