28-214913.scala

class A {
  def add(x: Int, y: Int): Int = {
    x + y
  }
}

val a = new A()
println(a.add(1, 2))

class B extends A {
  override def add(x: Int, y: Int): Int = {
    x + y + 2
  }
}

val b = new B()
println(b.add(1, 2))