How fractions are combined
- Add / subtract: a/b ± c/d = (ad ± bc) / bd
- Multiply: a/b × c/d = ac / bd
- Divide: a/b ÷ c/d = ad / bc
Mixed numbers are turned into improper fractions first (2 ¾ = 11/4), and every answer is reduced by the greatest common divisor of its top and bottom.