Subtract 18/90 from 4/42, Solve 4/42

Subtract 18/90 from 4/42

4/42 - 18/90 is -11/105.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 90 is 630

Next, find the equivalent fraction of both fractional numbers with denominator 630
For the 1st fraction, since 42 × 15 = 630,
4/42 = 4 × 15/42 × 15 = 60/630
Likewise, for the 2nd fraction, since 90 × 7 = 630,
18/90 = 18 × 7/90 × 7 = 126/630
Subtract the two like fractions:
60/630 - 126/630 = 60 - 126/630 = -66/630
After reducing the fraction, the answer is -11/105

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