Subtract 72/16 from 18/42, Solve 18/42

Subtract 72/16 from 18/42

1^st number: 18/42, 2^nd number: 4 8/16

18/42 - 72/16 is -57/14.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 16 is 336

Next, find the equivalent fraction of both fractional numbers with denominator 336
For the 1st fraction, since 42 × 8 = 336,
18/42 = 18 × 8/42 × 8 = 144/336
Likewise, for the 2nd fraction, since 16 × 21 = 336,
72/16 = 72 × 21/16 × 21 = 1512/336
Subtract the two like fractions:
144/336 - 1512/336 = 144 - 1512/336 = -1368/336
After reducing the fraction, the answer is -57/14

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