Subtract 15/8 from 12/42, Solve 12/42

Subtract 15/8 from 12/42

1^st number: 12/42, 2^nd number: 1 7/8

12/42 - 15/8 is -89/56.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 8 is 168

Next, find the equivalent fraction of both fractional numbers with denominator 168
For the 1st fraction, since 42 × 4 = 168,
12/42 = 12 × 4/42 × 4 = 48/168
Likewise, for the 2nd fraction, since 8 × 21 = 168,
15/8 = 15 × 21/8 × 21 = 315/168
Subtract the two like fractions:
48/168 - 315/168 = 48 - 315/168 = -267/168
After reducing the fraction, the answer is -89/56

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