Subtract 3/42 from 12/15, Solve 12/15

Subtract 3/42 from 12/15

12/15 - 3/42 is 51/70.

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,
3/42 = 3 × 5/42 × 5 = 15/210
Subtract the two like fractions:
168/210 - 15/210 = 168 - 15/210 = 153/210
After reducing the fraction, the answer is 51/70

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