Subtract 5/21 from 10/20, Solve 10/20

Subtract 5/21 from 10/20

10/20 - 5/21 is 11/42.

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

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 20 × 21 = 420,
10/20 = 10 × 21/20 × 21 = 210/420
Likewise, for the 2nd fraction, since 21 × 20 = 420,
5/21 = 5 × 20/21 × 20 = 100/420
Subtract the two like fractions:
210/420 - 100/420 = 210 - 100/420 = 110/420
After reducing the fraction, the answer is 11/42

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