How to fix these errors?

Question

C++ / C#

How to fix these errors?

main.cs(40,5): error CS0246: The type or namespace name `Trucks' could not be found. Are you missing an assembly reference?
main.cs(41,5): error CS0841: A local variable `man' cannot be used before it is declared
main.cs(42,24): error CS0841: A local variable `man' cannot be used before it is declared

using System;

class Cars {
    public int wheels = 4;
    public int speed = 135;
    public bool IsWorking = true;
    
    public void SetValues (int speed, int wheels) {
        this.speed  = speed;
        this.wheels = wheels;
    }
    public void GetValues () {
        Console.WriteLine("Speed is - " + this.speed + ", wheels is - " + this.wheels);
    }
    public Cars(int speed, int wheels, bool IsWorking) {
        this.speed      = speed;
        this.wheels     = wheels;
        this.IsWorking  = IsWorking;
    }
    public Cars () {}
    
    class Trucks : Cars { 
        public int passazir;
        
        public Trucks(int speed, int wheels, bool IsWorking, int passazir) : base (speed, wheels, IsWorking) {
            this.passazir = passazir;
        }
    }
}
class HelloWorld {
 (39) static void Main() {
 (40)   Trucks man = new Trucks (130, 8, true, 4);
  (41)  man.GetValues();
   (42) Console.WriteLine (man.passazir);
    
  }
}

Answer 1

Well, Trucks is declared in Cars. So you need to use it as Cars.Trucks. Or take out Trucks separately.
The remaining errors are consequences.