Subtract 7/8 from 21/70
21/70 - 7/8 is -23/40.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 8 is 280
Next, find the equivalent fraction of both fractional numbers with denominator 280 - For the 1st fraction, since 70 × 4 = 280,
21/70 = 21 × 4/70 × 4 = 84/280 - Likewise, for the 2nd fraction, since 8 × 35 = 280,
7/8 = 7 × 35/8 × 35 = 245/280 - Subtract the two like fractions:
84/280 - 245/280 = 84 - 245/280 = -161/280 - After reducing the fraction, the answer is -23/40
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/70-7/8 21/70-14/8 21/70-7/16 63/70-7/8 21/70-21/8 21/70-7/24 21/70-35/8 21/70-7/40 21/70-49/8 21/70-7/56