Subtract 81/90 from 20/42
20/42 - 81/90 is -89/210.
Steps for subtracting fractions
- 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 - For the 1st fraction, since 42 × 15 = 630,
20/42 = 20 × 15/42 × 15 = 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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