Subtract 18/8 from 21/90
1st number: 21/90, 2nd number: 2 2/8
21/90 - 18/8 is -121/60.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 8 is 360
Next, find the equivalent fraction of both fractional numbers with denominator 360 - For the 1st fraction, since 90 × 4 = 360,
21/90 = 21 × 4/90 × 4 = 84/360 - Likewise, for the 2nd fraction, since 8 × 45 = 360,
18/8 = 18 × 45/8 × 45 = 810/360 - Subtract the two like fractions:
84/360 - 810/360 = 84 - 810/360 = -726/360 - After reducing the fraction, the answer is -121/60
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/90-18/8 21/90-36/8 21/90-18/16 63/90-18/8 21/90-54/8 21/90-18/24 21/90-90/8 21/90-18/40 21/90-18/56