Subtract 60/21 from 30/80, Solve 30/80

Subtract 60/21 from 30/80

1^st number: 30/80, 2^nd number: 2 18/21

30/80 - 60/21 is -139/56.

Find the least common denominator or LCM of the two denominators:
LCM of 80 and 21 is 1680

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 80 × 21 = 1680,
30/80 = 30 × 21/80 × 21 = 630/1680
Likewise, for the 2nd fraction, since 21 × 80 = 1680,
60/21 = 60 × 80/21 × 80 = 4800/1680
Subtract the two like fractions:
630/1680 - 4800/1680 = 630 - 4800/1680 = -4170/1680
After reducing the fraction, the answer is -139/56

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