Increase over time,

I trying to get min from 1 to 5 and max from 10 to 20 in 30 sec. I dont know how. I know how to do it with one value but dont get it to work with two.

 public GameObject triangle;
 
 public Transform parentObject;
 public float max;
 public float min;


 void Start()
 {
     Invoke("spawn", 0.5f);

 }

 void spawn() {

     float random = Random.Range(min, max);

     GameObject myTriangleClone = Instantiate(triangle, gameObject.transform.position, gameObject.transform.rotation);
     myTriangleClone.transform.parent = parentObject;

     Invoke("spawn", random);
 }   

}