Subtract 21/18 from 28/21, Solve 1 7/21

Subtract 21/18 from 28/21

1^st number: 1 7/21, 2^nd number: 1 3/18

28/21 - 21/18 is 1/6.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 18 is 126

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 21 × 6 = 126,
28/21 = 28 × 6/21 × 6 = 168/126
Likewise, for the 2nd fraction, since 18 × 7 = 126,
21/18 = 21 × 7/18 × 7 = 147/126
Subtract the two like fractions:
168/126 - 147/126 = 168 - 147/126 = 21/126
After reducing the fraction, the answer is 1/6

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