Answers

Subtract 21/8 from 21/40

1^st number: 21/40, 2^nd number: 2 5/8

21/40 - 21/8 is -21/10.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 40 and 8 is 40
   
   Next, find the equivalent fraction of both fractional numbers with denominator 40
2. For the 1st fraction, since 40 × 1 = 40,
   21/40 = 21 × 1/40 × 1 = 21/40
3. Likewise, for the 2nd fraction, since 8 × 5 = 40,
   21/8 = 21 × 5/8 × 5 = 105/40
4. Subtract the two like fractions:
   21/40 - 105/40 = 21 - 105/40 = -84/40
5. After reducing the fraction, the answer is -21/10

MathStep (Works offline)

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

Related: ⁴²/₄₀-²¹/₈ ²¹/₄₀-⁴²/₈ ²¹/₈₀-²¹/₈ ²¹/₄₀-²¹/₁₆ ⁶³/₄₀-²¹/₈ ²¹/₄₀-⁶³/₈ ²¹/₄₀-²¹/₂₄ ²¹/₄₀-²¹/₄₀ ²¹/₄₀-²¹/₅₆

Subtract Fractions Calculator