Subtract 30/40 from 4/42, Solve 4/42

Subtract 30/40 from 4/42

4/42 - 30/40 is -55/84.

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,
4/42 = 4 × 20/42 × 20 = 80/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
30/40 = 30 × 21/40 × 21 = 630/840
Subtract the two like fractions:
80/840 - 630/840 = 80 - 630/840 = -550/840
After reducing the fraction, the answer is -55/84

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