Subtract 18/10 from 21/28, Solve 21/28

Subtract 18/10 from 21/28

1^st number: 21/28, 2^nd number: 1 8/10

21/28 - 18/10 is -21/20.

Find the least common denominator or LCM of the two denominators:
LCM of 28 and 10 is 140

Next, find the equivalent fraction of both fractional numbers with denominator 140
For the 1st fraction, since 28 × 5 = 140,
21/28 = 21 × 5/28 × 5 = 105/140
Likewise, for the 2nd fraction, since 10 × 14 = 140,
18/10 = 18 × 14/10 × 14 = 252/140
Subtract the two like fractions:
105/140 - 252/140 = 105 - 252/140 = -147/140
After reducing the fraction, the answer is -21/20

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