Subtract 2/5 from 28/21, Solve 1 7/21

Subtract 2/5 from 28/21

1^st number: 1 7/21, 2^nd number: 2/5

28/21 - 2/5 is 14/15.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 5 is 105

Next, find the equivalent fraction of both fractional numbers with denominator 105
For the 1st fraction, since 21 × 5 = 105,
28/21 = 28 × 5/21 × 5 = 140/105
Likewise, for the 2nd fraction, since 5 × 21 = 105,
2/5 = 2 × 21/5 × 21 = 42/105
Subtract the two like fractions:
140/105 - 42/105 = 140 - 42/105 = 98/105
After reducing the fraction, the answer is 14/15

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