Subtract 15/8 from 18/42
1st number: 18/42, 2nd number: 1 7/8
18/42 - 15/8 is -81/56.
Steps for subtracting fractions
- 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,
18/42 = 18 × 4/42 × 4 = 72/168 - Likewise, for the 2nd fraction, since 8 × 21 = 168,
15/8 = 15 × 21/8 × 21 = 315/168 - Subtract the two like fractions:
72/168 - 315/168 = 72 - 315/168 = -243/168 - After reducing the fraction, the answer is -81/56
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