Subtract 4/30 from 20/21, Solve 20/21

Subtract 4/30 from 20/21

20/21 - 4/30 is 86/105.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 30 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 21 × 10 = 210,
20/21 = 20 × 10/21 × 10 = 200/210
Likewise, for the 2nd fraction, since 30 × 7 = 210,
4/30 = 4 × 7/30 × 7 = 28/210
Subtract the two like fractions:
200/210 - 28/210 = 200 - 28/210 = 172/210
After reducing the fraction, the answer is 86/105

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