Subtract 90/42 from 81/64, Solve 1 17/64

Subtract 90/42 from 81/64

1^st number: 1 17/64, 2^nd number: 2 6/42

81/64 - 90/42 is -393/448.

Find the least common denominator or LCM of the two denominators:
LCM of 64 and 42 is 1344

Next, find the equivalent fraction of both fractional numbers with denominator 1344
For the 1st fraction, since 64 × 21 = 1344,
81/64 = 81 × 21/64 × 21 = 1701/1344
Likewise, for the 2nd fraction, since 42 × 32 = 1344,
90/42 = 90 × 32/42 × 32 = 2880/1344
Subtract the two like fractions:
1701/1344 - 2880/1344 = 1701 - 2880/1344 = -1179/1344
After reducing the fraction, the answer is -393/448

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