Subtract 18/72 from 3/42, Solve 3/42

Subtract 18/72 from 3/42

3/42 - 18/72 is -5/28.

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

Next, find the equivalent fraction of both fractional numbers with denominator 504
For the 1st fraction, since 42 × 12 = 504,
3/42 = 3 × 12/42 × 12 = 36/504
Likewise, for the 2nd fraction, since 72 × 7 = 504,
18/72 = 18 × 7/72 × 7 = 126/504
Subtract the two like fractions:
36/504 - 126/504 = 36 - 126/504 = -90/504
After reducing the fraction, the answer is -5/28

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