Subtract 3/72 from 20/21
20/21 - 3/72 is 51/56.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 72 is 504
Next, find the equivalent fraction of both fractional numbers with denominator 504 - For the 1st fraction, since 21 × 24 = 504,
20/21 = 20 × 24/21 × 24 = 480/504 - Likewise, for the 2nd fraction, since 72 × 7 = 504,
3/72 = 3 × 7/72 × 7 = 21/504 - Subtract the two like fractions:
480/504 - 21/504 = 480 - 21/504 = 459/504 - After reducing the fraction, the answer is 51/56
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