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

Subtract 1/21 from 42/72

42/72 - 1/21 is 15/28.

Find the least common denominator or LCM of the two denominators:
LCM of 72 and 21 is 504

Next, find the equivalent fraction of both fractional numbers with denominator 504
For the 1st fraction, since 72 × 7 = 504,
42/72 = 42 × 7/72 × 7 = 294/504
Likewise, for the 2nd fraction, since 21 × 24 = 504,
1/21 = 1 × 24/21 × 24 = 24/504
Subtract the two like fractions:
294/504 - 24/504 = 294 - 24/504 = 270/504
After reducing the fraction, the answer is 15/28

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