Subtract 81/21 from 4/40, Solve 4/40

Subtract 81/21 from 4/40

1^st number: 4/40, 2^nd number: 3 18/21

4/40 - 81/21 is -263/70.

Find the least common denominator or LCM of the two denominators:
LCM of 40 and 21 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 40 × 21 = 840,
4/40 = 4 × 21/40 × 21 = 84/840
Likewise, for the 2nd fraction, since 21 × 40 = 840,
81/21 = 81 × 40/21 × 40 = 3240/840
Subtract the two like fractions:
84/840 - 3240/840 = 84 - 3240/840 = -3156/840
After reducing the fraction, the answer is -263/70

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