Subtract 20/21 from 7/90
7/90 - 20/21 is -551/630.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
7/90 = 7 × 7/90 × 7 = 49/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
20/21 = 20 × 30/21 × 30 = 600/630 - Subtract the two like fractions:
49/630 - 600/630 = 49 - 600/630 = -551/630
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