Subtract 7/5 from 21/42, Solve 21/42

Subtract 7/5 from 21/42

1^st number: 21/42, 2^nd number: 1 2/5

21/42 - 7/5 is -9/10.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 5 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 5 × 42 = 210,
7/5 = 7 × 42/5 × 42 = 294/210
Subtract the two like fractions:
105/210 - 294/210 = 105 - 294/210 = -189/210
After reducing the fraction, the answer is -9/10

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