Subtract 30/42 from 12/15, Solve 12/15

Subtract 30/42 from 12/15

12/15 - 30/42 is 3/35.

Find the least common denominator or LCM of the two denominators:
LCM of 15 and 42 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 15 × 14 = 210,
12/15 = 12 × 14/15 × 14 = 168/210
Likewise, for the 2nd fraction, since 42 × 5 = 210,
30/42 = 30 × 5/42 × 5 = 150/210
Subtract the two like fractions:
168/210 - 150/210 = 168 - 150/210 = 18/210
After reducing the fraction, the answer is 3/35

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