Subtract 18/21 from 42/90
42/90 - 18/21 is -41/105.
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,
42/90 = 42 × 7/90 × 7 = 294/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
18/21 = 18 × 30/21 × 30 = 540/630 - Subtract the two like fractions:
294/630 - 540/630 = 294 - 540/630 = -246/630 - After reducing the fraction, the answer is -41/105
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