Subtract 30/10 from 40/42, Solve 40/42

Subtract 30/10 from 40/42

1^st number: 40/42, 2^nd number: 3 0/10

40/42 - 30/10 is -43/21.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 10 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 10 × 21 = 210,
30/10 = 30 × 21/10 × 21 = 630/210
Subtract the two like fractions:
200/210 - 630/210 = 200 - 630/210 = -430/210
After reducing the fraction, the answer is -43/21

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