Subtract 7/40 from 81/42, Solve 1 39/42

Subtract 7/40 from 81/42

1^st number: 1 39/42, 2^nd number: 7/40

81/42 - 7/40 is 491/280.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 42 × 20 = 840,
81/42 = 81 × 20/42 × 20 = 1620/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
7/40 = 7 × 21/40 × 21 = 147/840
Subtract the two like fractions:
1620/840 - 147/840 = 1620 - 147/840 = 1473/840
After reducing the fraction, the answer is 491/280
In mixed form: 1211/280

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