I am new to the creation in C # . I do not know how to solve this problem . Can you help ?
A - B means nothing as you dont store the result.
C = A - B has a lot more meaning.
You mean to do velocity = new vector.
Or if you were trying to take away from the velocity you mean
velocity = velocity - new vector.
Try changing
GetComponent<Rigidbody2d>().velocity-=new Vector2(0, jumphight*time.deltatime);
Or
GetComponent<Rigidbody2d>().velocity-=new Vector2(0, jumphight)*time.deltatime;
Or Simply How meat5000 said
GetComponent<Rigidbody2d>().velocity-=new Vector2(0, jumphight);