Subtract 81/90 from 10/21
10/21 - 81/90 is -89/210.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 21 × 30 = 630,
10/21 = 10 × 30/21 × 30 = 300/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
81/90 = 81 × 7/90 × 7 = 567/630 - Subtract the two like fractions:
300/630 - 567/630 = 300 - 567/630 = -267/630 - After reducing the fraction, the answer is -89/210
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