Answers

Subtract 81/84 from 42/90

42/90 - 81/84 is -209/420.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 90 and 84 is 1260
   
   Next, find the equivalent fraction of both fractional numbers with denominator 1260
2. For the 1st fraction, since 90 × 14 = 1260,
   42/90 = 42 × 14/90 × 14 = 588/1260
3. Likewise, for the 2nd fraction, since 84 × 15 = 1260,
   81/84 = 81 × 15/84 × 15 = 1215/1260
4. Subtract the two like fractions:
   588/1260 - 1215/1260 = 588 - 1215/1260 = -627/1260
5. After reducing the fraction, the answer is -209/420

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad

Related: ⁸⁴/₉₀-⁸¹/₈₄

Subtract Fractions Calculator