Subtract 72/70 from 40/42, Solve 40/42

Subtract 72/70 from 40/42

1^st number: 40/42, 2^nd number: 1 2/70

40/42 - 72/70 is -8/105.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 70 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 42 × 5 = 210,
40/42 = 40 × 5/42 × 5 = 200/210
Likewise, for the 2nd fraction, since 70 × 3 = 210,
72/70 = 72 × 3/70 × 3 = 216/210
Subtract the two like fractions:
200/210 - 216/210 = 200 - 216/210 = -16/210
After reducing the fraction, the answer is -8/105

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