Subtract 80/50 from 21/84, Solve 21/84

Subtract 80/50 from 21/84

1^st number: 21/84, 2^nd number: 1 30/50

21/84 - 80/50 is -27/20.

Find the least common denominator or LCM of the two denominators:
LCM of 84 and 50 is 2100

Next, find the equivalent fraction of both fractional numbers with denominator 2100
For the 1st fraction, since 84 × 25 = 2100,
21/84 = 21 × 25/84 × 25 = 525/2100
Likewise, for the 2nd fraction, since 50 × 42 = 2100,
80/50 = 80 × 42/50 × 42 = 3360/2100
Subtract the two like fractions:
525/2100 - 3360/2100 = 525 - 3360/2100 = -2835/2100
After reducing the fraction, the answer is -27/20

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