Subtract 70/15 from 21/42, Solve 21/42

Subtract 70/15 from 21/42

1^st number: 21/42, 2^nd number: 4 10/15

21/42 - 70/15 is -25/6.

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

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 42 × 5 = 210,
21/42 = 21 × 5/42 × 5 = 105/210
Likewise, for the 2nd fraction, since 15 × 14 = 210,
70/15 = 70 × 14/15 × 14 = 980/210
Subtract the two like fractions:
105/210 - 980/210 = 105 - 980/210 = -875/210
After reducing the fraction, the answer is -25/6

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