Subtract 63/42 from 27/20, Solve 1 7/20

Subtract 63/42 from 27/20

1^st number: 1 7/20, 2^nd number: 1 21/42

27/20 - 63/42 is -3/20.

Find the least common denominator or LCM of the two denominators:
LCM of 20 and 42 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 20 × 21 = 420,
27/20 = 27 × 21/20 × 21 = 567/420
Likewise, for the 2nd fraction, since 42 × 10 = 420,
63/42 = 63 × 10/42 × 10 = 630/420
Subtract the two like fractions:
567/420 - 630/420 = 567 - 630/420 = -63/420
After reducing the fraction, the answer is -3/20

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