void setup() {
  Serial.begin(9600);
    float result = 0 ; 
    int a = 9;
    float b = 4.5;
    result = sum_func (a,b) ; // function call
    Serial.print("result = "); 
    Serial.println(result); 
}

void loop() {
    
}

float sum_func (int x, float y) {// function declaration 
  float z = 0; 
  Serial.print("x =");  Serial.println(x); 
  Serial.print("y =");  Serial.println(y); 
  z = x+y ; 
  Serial.print("z =");  Serial.println(z); 
  return z; // return the value
}