Subtract 5/20 from 2/21, Solve 2/21

Subtract 5/20 from 2/21

2/21 - 5/20 is -13/84.

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,
2/21 = 2 × 20/21 × 20 = 40/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
5/20 = 5 × 21/20 × 21 = 105/420
Subtract the two like fractions:
40/420 - 105/420 = 40 - 105/420 = -65/420
After reducing the fraction, the answer is -13/84

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