Subtract 80/42 from 18/90, Solve 18/90

Subtract 80/42 from 18/90

1^st number: 18/90, 2^nd number: 1 38/42

18/90 - 80/42 is -179/105.

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

Next, find the equivalent fraction of both fractional numbers with denominator 630
For the 1st fraction, since 90 × 7 = 630,
18/90 = 18 × 7/90 × 7 = 126/630
Likewise, for the 2nd fraction, since 42 × 15 = 630,
80/42 = 80 × 15/42 × 15 = 1200/630
Subtract the two like fractions:
126/630 - 1200/630 = 126 - 1200/630 = -1074/630
After reducing the fraction, the answer is -179/105

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