Subtract 18/42 from 21/90
21/90 - 18/42 is -41/210.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 42 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
21/90 = 21 × 7/90 × 7 = 147/630 - Likewise, for the 2nd fraction, since 42 × 15 = 630,
18/42 = 18 × 15/42 × 15 = 270/630 - Subtract the two like fractions:
147/630 - 270/630 = 147 - 270/630 = -123/630 - After reducing the fraction, the answer is -41/210
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