Subtract 49/42 from 21/90, Solve 21/90

Subtract 49/42 from 21/90

1^st number: 21/90, 2^nd number: 1 7/42

21/90 - 49/42 is -14/15.

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,
21/90 = 21 × 7/90 × 7 = 147/630
Likewise, for the 2nd fraction, since 42 × 15 = 630,
49/42 = 49 × 15/42 × 15 = 735/630
Subtract the two like fractions:
147/630 - 735/630 = 147 - 735/630 = -588/630
After reducing the fraction, the answer is -14/15

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