Subtract 15/20 from 28/21, Solve 1 7/21

Subtract 15/20 from 28/21

1^st number: 1 7/21, 2^nd number: 15/20

28/21 - 15/20 is 7/12.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 21 × 20 = 420,
28/21 = 28 × 20/21 × 20 = 560/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
15/20 = 15 × 21/20 × 21 = 315/420
Subtract the two like fractions:
560/420 - 315/420 = 560 - 315/420 = 245/420
After reducing the fraction, the answer is 7/12

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