Subtract 42/8 from 15/21, Solve 15/21

Subtract 42/8 from 15/21

1^st number: 15/21, 2^nd number: 5 2/8

15/21 - 42/8 is -127/28.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 8 is 168

Next, find the equivalent fraction of both fractional numbers with denominator 168
For the 1st fraction, since 21 × 8 = 168,
15/21 = 15 × 8/21 × 8 = 120/168
Likewise, for the 2nd fraction, since 8 × 21 = 168,
42/8 = 42 × 21/8 × 21 = 882/168
Subtract the two like fractions:
120/168 - 882/168 = 120 - 882/168 = -762/168
After reducing the fraction, the answer is -127/28

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