Answers

Add 72/90 and 45/12

1^st number: 72/90, 2^nd number: 3 9/12

72/90 + 45/12 is 91/20.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 90 and 12 is 180
2. For the 1st fraction, since 90 × 2 = 180,
   72/90 = 72 × 2/90 × 2 = 144/180
3. Likewise, for the 2nd fraction, since 12 × 15 = 180,
   45/12 = 45 × 15/12 × 15 = 675/180
4. Add the two fractions:
   144/180 + 675/180 = 144 + 675/180 = 819/180
5. 819/180 simplified gives 91/20
6. So, 72/90 + 45/12 = 91/20
   In mixed form: 411/20

MathStep (Works offline)

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

Related: ⁷²/₉₀+⁹⁰/₁₂ ⁷²/₉₀+⁴⁵/₂₄ ⁷²/₉₀+⁴⁵/₃₆ ⁷²/₉₀+⁴⁵/₆₀ ⁷²/₉₀+⁴⁵/₈₄

Add Fractions Calculator