void setup() {
  Serial.begin(115200);
  double distanceDelta = 0;
  int ledsPerMeter = 100;

  int factor = 3;
  double constValue = 0.15;

  double to = factor * constValue; // works not
  double from = to - constValue;
  double a = from - distanceDelta;
  double b = a * ledsPerMeter;
  double c = b + 1;
  int d = c;

  Serial.printf("factor(3)=%d\n", factor);
  Serial.printf("constValue(0.15)=%f\n", constValue);
  Serial.printf("to(0.45)=%f\n", to);
  Serial.printf("from(0.3)=%f\n", from);
  Serial.printf("a(0.3=)%f\n", a);
  Serial.printf("b(30)=%f\n", b);
  Serial.printf("c(31.0)=%.50f\n", c);
  Serial.printf("d(31)=%d\n", d);
  Serial.printf("d+1(32)=%d\n", d + 1);
}

void loop() {}