Subtract 54/90 from 20/42
20/42 - 54/90 is -13/105.
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,
54/90 = 54 × 7/90 × 7 = 378/630 - Subtract the two like fractions:
300/630 - 378/630 = 300 - 378/630 = -78/630 - After reducing the fraction, the answer is -13/105
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