Subtract 2/40 from 3/21, Solve 3/21

Subtract 2/40 from 3/21

3/21 - 2/40 is 13/140.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 21 × 40 = 840,
3/21 = 3 × 40/21 × 40 = 120/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
2/40 = 2 × 21/40 × 21 = 42/840
Subtract the two like fractions:
120/840 - 42/840 = 120 - 42/840 = 78/840
After reducing the fraction, the answer is 13/140

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