int x=3;
int y =7;
int z;
int WaitT=670;
String my = " + " ;

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
// z=x+y;
Serial.print(x);
Serial.print(my);
Serial.print(y);
Serial.print(" = ");
z=x+y;
Serial.println(z);
delay(WaitT);
}