Subtract 21/42 from 12/80
12/80 - 21/42 is -7/20.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 80 and 42 is 1680
Next, find the equivalent fraction of both fractional numbers with denominator 1680 - For the 1st fraction, since 80 × 21 = 1680,
12/80 = 12 × 21/80 × 21 = 252/1680 - Likewise, for the 2nd fraction, since 42 × 40 = 1680,
21/42 = 21 × 40/42 × 40 = 840/1680 - Subtract the two like fractions:
252/1680 - 840/1680 = 252 - 840/1680 = -588/1680 - After reducing the fraction, the answer is -7/20
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/80-21/42 12/80-21/84 36/80-21/42 12/80-63/42 60/80-21/42 84/80-21/42