title: what should I do if I want to set the default value of my parameter if the parameter has null value
body: <p>How to set the default value of the variable <code>valueC</code> if the <code>valueC</code> is <code>null</code>, and then get the default value for <code>valueC = 100</code> in  elvis operator.</p>
  
  <pre><code>// Here my full code 
  
  fun main() {
      val valueA = 65
      val valueB = 52
      val valueC = 78
  
      val result = calculate(valueA, valueB, valueC)
  
      // TODO 3
      println("Result is $result")
  }
  
  fun calculate(valueA: Int, valueB: Int, valueC: Int?=100): String {
      // TODO 1
      val result = valueC?.let { valueA + (valueB - valueC) } ?: 100
      return generateResult(result)
  }
  
  // TODO 2
  fun generateResult(result: Int) = result.toString()
  </code></pre>