Subtract 4/20 from 3/42, Solve 3/42

Subtract 4/20 from 3/42

3/42 - 4/20 is -9/70.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 42 × 10 = 420,
3/42 = 3 × 10/42 × 10 = 30/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
4/20 = 4 × 21/20 × 21 = 84/420
Subtract the two like fractions:
30/420 - 84/420 = 30 - 84/420 = -54/420
After reducing the fraction, the answer is -9/70

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