Subtract 1/42 from 21/72, Solve 21/72

Subtract 1/42 from 21/72

21/72 - 1/42 is 15/56.

Find the least common denominator or LCM of the two denominators:
LCM of 72 and 42 is 504

Next, find the equivalent fraction of both fractional numbers with denominator 504
For the 1st fraction, since 72 × 7 = 504,
21/72 = 21 × 7/72 × 7 = 147/504
Likewise, for the 2nd fraction, since 42 × 12 = 504,
1/42 = 1 × 12/42 × 12 = 12/504
Subtract the two like fractions:
147/504 - 12/504 = 147 - 12/504 = 135/504
After reducing the fraction, the answer is 15/56

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