Subtract 42/30 from 21/80, Solve 21/80

Subtract 42/30 from 21/80

1^st number: 21/80, 2^nd number: 1 12/30

21/80 - 42/30 is -91/80.

Find the least common denominator or LCM of the two denominators:
LCM of 80 and 30 is 240

Next, find the equivalent fraction of both fractional numbers with denominator 240
For the 1st fraction, since 80 × 3 = 240,
21/80 = 21 × 3/80 × 3 = 63/240
Likewise, for the 2nd fraction, since 30 × 8 = 240,
42/30 = 42 × 8/30 × 8 = 336/240
Subtract the two like fractions:
63/240 - 336/240 = 63 - 336/240 = -273/240
After reducing the fraction, the answer is -91/80

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