Subtract 30/90 from 28/70
28/70 - 30/90 is 1/15.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 70 × 9 = 630,
28/70 = 28 × 9/70 × 9 = 252/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
30/90 = 30 × 7/90 × 7 = 210/630 - Subtract the two like fractions:
252/630 - 210/630 = 252 - 210/630 = 42/630 - After reducing the fraction, the answer is 1/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 56/70-30/90 28/70-60/90 84/70-30/90