Simple PHP calculator

Question

I\'m creating a basic PHP calculator that lets you enter two values and chose your operator then displays the answer. Everything is working fine except it\'s not outputting

Answer 1

    
    
        
        
    
    
    HTML Code is here:

         

            
            
            
               None
               Add
               Subtract
               Multiply
               Divide
               Square
            
            Calculate
         

    PHP Code:

        
        enter code here