Subtract 4/80 from 63/42, Solve 1 21/42

Subtract 4/80 from 63/42

1^st number: 1 21/42, 2^nd number: 4/80

63/42 - 4/80 is 29/20.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 80 is 1680

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 42 × 40 = 1680,
63/42 = 63 × 40/42 × 40 = 2520/1680
Likewise, for the 2nd fraction, since 80 × 21 = 1680,
4/80 = 4 × 21/80 × 21 = 84/1680
Subtract the two like fractions:
2520/1680 - 84/1680 = 2520 - 84/1680 = 2436/1680
After reducing the fraction, the answer is 29/20
In mixed form: 19/20

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