I need some help with PHP classes

Question

I have this UML diagram but i don't know how to write the right code for it :(

-----Calculator-------
+ add : string
+ sub : string
+ count : int
+ num1 : int
+ num2 : int
--------------
Calculator(int,int,string,string)
+add():
+sub():
______________________

------$cal:Calculator------
+self:: $ add : Add
+self:: $sub : Sub
++self:: count :int
+ num1 : 5
+ num2 : 2

Answer 1

https://www.sololearn.com/learn/984/?ref=app