Subtract 12/21 from 15/90
15/90 - 12/21 is -17/42.
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,
15/90 = 15 × 7/90 × 7 = 105/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
12/21 = 12 × 30/21 × 30 = 360/630 - Subtract the two like fractions:
105/630 - 360/630 = 105 - 360/630 = -255/630 - After reducing the fraction, the answer is -17/42
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