Answers

Subtract 20/90 from 81/42

1^st number: 1 39/42, 2^nd number: 20/90

81/42 - 20/90 is 215/126.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 42 and 90 is 630
   
   Next, find the equivalent fraction of both fractional numbers with denominator 630
2. For the 1st fraction, since 42 × 15 = 630,
   81/42 = 81 × 15/42 × 15 = 1215/630
3. Likewise, for the 2nd fraction, since 90 × 7 = 630,
   20/90 = 20 × 7/90 × 7 = 140/630
4. Subtract the two like fractions:
   1215/630 - 140/630 = 1215 - 140/630 = 1075/630
5. After reducing the fraction, the answer is 215/126
6. In mixed form: 189/126

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