Answers

Subtract 5/20 from 21/90

21/90 - 5/20 is -1/60.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 90 and 20 is 180
   
   Next, find the equivalent fraction of both fractional numbers with denominator 180
2. For the 1st fraction, since 90 × 2 = 180,
   21/90 = 21 × 2/90 × 2 = 42/180
3. Likewise, for the 2nd fraction, since 20 × 9 = 180,
   5/20 = 5 × 9/20 × 9 = 45/180
4. Subtract the two like fractions:
   42/180 - 45/180 = 42 - 45/180 = -3/180
5. After reducing the fraction, the answer is -1/60

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