Type Alias

type Age = int
type Price = float
type Fraction = int * int

let diffAge (a1: Age) (a2: Age) : Age =
    a1 - a2

let addPrice (p1: Price) (p2: Price) : Price =
    p1 + p2

let multiplyFraction (f1: Fraction) (f2: Fraction) : Fraction =
    (fst f1 * fst f2, snd f1 * snd f2)