Answers

Subtract 80/21 from 90/45

1^st number: 2 0/45, 2^nd number: 3 17/21

90/45 - 80/21 is -38/21.

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,
   90/45 = 90 × 7/45 × 7 = 630/315
3. Likewise, for the 2nd fraction, since 21 × 15 = 315,
   80/21 = 80 × 15/21 × 15 = 1200/315
4. Subtract the two like fractions:
   630/315 - 1200/315 = 630 - 1200/315 = -570/315
5. After reducing the fraction, the answer is -38/21

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