Rational.scala

class Rational(n: Int, d: Int) {
  require(d != 0, "Denominator cannot be 0")

  println("My rational is created")

  val num = n
  val denom = d

  def this(n: Int) = this(n, 1)
  
  override def toString = s"$n/$d"

  def +(that: Rational): Rational = {
    new Rational(
        n * that.denom + that.num * d,
        d * that.denom
    )
  }
}