Here is my sample solution for the challenge. Of course, there are many different ways of solving this.

fun main(){

  val iphone = MobilePhone("iOS", "Apple", "iPhone 12")

  val galaxyS20 = MobilePhone("Android","Samsung", "Galaxy S20")

  val mateXS = MobilePhone("Android", "Huawei", "Mate X S")

}



class MobilePhone(osName: String, brand: String, model: String){



  private var battery = 30



  init {

    println("The phone $model from $brand uses $osName as its Operating System")

  }



  fun chargeBattery(chargedBy: Int){

    println("Battery was at $battery and is at ${battery+chargedBy} now")

    battery += chargedBy

  }

}