Subtract 42/90 from 30/80
30/80 - 42/90 is -11/120.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 80 and 90 is 720
Next, find the equivalent fraction of both fractional numbers with denominator 720 - For the 1st fraction, since 80 × 9 = 720,
30/80 = 30 × 9/80 × 9 = 270/720 - Likewise, for the 2nd fraction, since 90 × 8 = 720,
42/90 = 42 × 8/90 × 8 = 336/720 - Subtract the two like fractions:
270/720 - 336/720 = 270 - 336/720 = -66/720 - After reducing the fraction, the answer is -11/120
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 60/80-42/90 30/80-84/90 90/80-42/90