Subtract 20/40 from 10/42, Solve 10/42

Subtract 20/40 from 10/42

10/42 - 20/40 is -11/42.

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,
10/42 = 10 × 20/42 × 20 = 200/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
20/40 = 20 × 21/40 × 21 = 420/840
Subtract the two like fractions:
200/840 - 420/840 = 200 - 420/840 = -220/840
After reducing the fraction, the answer is -11/42

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