Subtract 18/40 from 5/42, Solve 5/42

Subtract 18/40 from 5/42

5/42 - 18/40 is -139/420.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 42 × 20 = 840,
5/42 = 5 × 20/42 × 20 = 100/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
18/40 = 18 × 21/40 × 21 = 378/840
Subtract the two like fractions:
100/840 - 378/840 = 100 - 378/840 = -278/840
After reducing the fraction, the answer is -139/420

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