Subtract 21/7 from 1/80, Solve 1/80

Subtract 21/7 from 1/80

1^st number: 1/80, 2^nd number: 3 0/7

1/80 - 21/7 is -239/80.

Find the least common denominator or LCM of the two denominators:
LCM of 80 and 7 is 560

Next, find the equivalent fraction of both fractional numbers with denominator 560
For the 1st fraction, since 80 × 7 = 560,
1/80 = 1 × 7/80 × 7 = 7/560
Likewise, for the 2nd fraction, since 7 × 80 = 560,
21/7 = 21 × 80/7 × 80 = 1680/560
Subtract the two like fractions:
7/560 - 1680/560 = 7 - 1680/560 = -1673/560
After reducing the fraction, the answer is -239/80

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