Subtract 12/80 from 4/42, Solve 4/42

Subtract 12/80 from 4/42

4/42 - 12/80 is -23/420.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 80 is 1680

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 42 × 40 = 1680,
4/42 = 4 × 40/42 × 40 = 160/1680
Likewise, for the 2nd fraction, since 80 × 21 = 1680,
12/80 = 12 × 21/80 × 21 = 252/1680
Subtract the two like fractions:
160/1680 - 252/1680 = 160 - 252/1680 = -92/1680
After reducing the fraction, the answer is -23/420

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