kotlin substraction

fun main(args:Array<String>)
{
    var firstno=100    var secno=20    var result:Int?
    result=firstno-secno
    println("THE SUM IS $result")

    //or    println("THE SUM IS ${firstno - secno }")
}

• OUTPUT >>>
• THE SUM IS 30
• THE SUM IS 150
• 
  
• Process finished with exit code 0