Subtract 18/20 from 21/90
21/90 - 18/20 is -2/3.
Steps for subtracting fractions
- 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 - For the 1st fraction, since 90 × 2 = 180,
21/90 = 21 × 2/90 × 2 = 42/180 - Likewise, for the 2nd fraction, since 20 × 9 = 180,
18/20 = 18 × 9/20 × 9 = 162/180 - Subtract the two like fractions:
42/180 - 162/180 = 42 - 162/180 = -120/180 - After reducing the fraction, the answer is -2/3
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