Subtract 72/70 from 42/90, Solve 42/90

Subtract 72/70 from 42/90

1^st number: 42/90, 2^nd number: 1 2/70

42/90 - 72/70 is -59/105.

Find the least common denominator or LCM of the two denominators:
LCM of 90 and 70 is 630

Next, find the equivalent fraction of both fractional numbers with denominator 630
For the 1st fraction, since 90 × 7 = 630,
42/90 = 42 × 7/90 × 7 = 294/630
Likewise, for the 2nd fraction, since 70 × 9 = 630,
72/70 = 72 × 9/70 × 9 = 648/630
Subtract the two like fractions:
294/630 - 648/630 = 294 - 648/630 = -354/630
After reducing the fraction, the answer is -59/105

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