Answers

Subtract 90/84 from 20/45

1^st number: 20/45, 2^nd number: 1 6/84

20/45 - 90/84 is -79/126.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 45 and 84 is 1260
   
   Next, find the equivalent fraction of both fractional numbers with denominator 1260
2. For the 1st fraction, since 45 × 28 = 1260,
   20/45 = 20 × 28/45 × 28 = 560/1260
3. Likewise, for the 2nd fraction, since 84 × 15 = 1260,
   90/84 = 90 × 15/84 × 15 = 1350/1260
4. Subtract the two like fractions:
   560/1260 - 1350/1260 = 560 - 1350/1260 = -790/1260
5. After reducing the fraction, the answer is -79/126

MathStep (Works offline)

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

Related: ⁴⁰/₄₅-⁹⁰/₈₄ ²⁰/₉₀-⁹⁰/₈₄ ⁶⁰/₄₅-⁹⁰/₈₄

Subtract Fractions Calculator