Answers

Subtract 28/21 from 20/45

1^st number: 20/45, 2^nd number: 1 7/21

20/45 - 28/21 is -8/9.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 45 and 21 is 315
   
   Next, find the equivalent fraction of both fractional numbers with denominator 315
2. For the 1st fraction, since 45 × 7 = 315,
   20/45 = 20 × 7/45 × 7 = 140/315
3. Likewise, for the 2nd fraction, since 21 × 15 = 315,
   28/21 = 28 × 15/21 × 15 = 420/315
4. Subtract the two like fractions:
   140/315 - 420/315 = 140 - 420/315 = -280/315
5. After reducing the fraction, the answer is -8/9

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